- Innate immunity refers to nonspecific defense mechanisms present from birth that provide immediate resistance to pathogens. It includes physical and chemical barriers as well as cellular responses like phagocytosis.
- Adaptive immunity develops later in life and involves antigen-specific immune responses mediated by lymphocytes. It is more complex than innate immunity and includes immunological memory.
- The immune system consists of both innate and adaptive immunity. Innate responses provide initial defense against infection while adaptive responses provide acquired, antigen-specific immunity. Memory cells generated during adaptive responses enable faster responses upon reexposure.
The organism possesses powerful mechanism to avoid immune auto aggression, The acquired ability of the immune system to avoid responsiveness to self antigens is defined as тАШ toleranceтАЩ It is obtained by the cooperative efforts of central and peripheral mechanisms, which allow a rapid and efficient removal of pathogens ( Virus and Bacteria ) in the absence of self-recognition, It is a dysfunction of the immune system. The immune system protects you from disease and infection. Sometimes, though, the immune system can produce autoantibodies that attack healthy cells, tissues, and organs. This can lead to autoimmune disease.Autoimmune diseases can affect any part of the body
The organism possesses powerful mechanism to avoid immune auto aggression, The acquired ability of the immune system to avoid responsiveness to self antigens is defined as тАШ toleranceтАЩ It is obtained by the cooperative efforts of central and peripheral mechanisms, which allow a rapid and efficient removal of pathogens ( Virus and Bacteria ) in the absence of self-recognition, It is a dysfunction of the immune system. The immune system protects you from disease and infection. Sometimes, though, the immune system can produce autoantibodies that attack healthy cells, tissues, and organs. This can lead to autoimmune disease.Autoimmune diseases can affect any part of the body
By DR. MANPREET KAUR BEHL.
Description of classificaton of immune system, immune cells, HLA, MHC complexes, antigen presentation, t-cell responses and b-cell responses, antibody, isotype switching, hypersenstivity reactions etc.
Adaptive immunity is an immunity that occurs after exposure to an antigen either from a pathogen or a vaccination. This part of the immune system is activated when the innate immune response is insufficient to control an infection. In fact, without information from the innate immune system, the adaptive response could not be mobilized. There are two types of adaptive responses: the cell-mediated immune response, which is carried out by T cells, and the humoral immune response, which is controlled by activated B cells and antibodies.
introduction of adaptive immunity. classification of adaptive immunity, factor affecting it and mechanism of adaptive immunity comparison between adaptive immunity and innate immunity. characteristic of adaptive immunity . cell mediated immune responses immunoglobulins
types of immunoglobulins. functions of immunoglobulins, hypersensitivity reactions
By DR. MANPREET KAUR BEHL.
Description of classificaton of immune system, immune cells, HLA, MHC complexes, antigen presentation, t-cell responses and b-cell responses, antibody, isotype switching, hypersenstivity reactions etc.
Adaptive immunity is an immunity that occurs after exposure to an antigen either from a pathogen or a vaccination. This part of the immune system is activated when the innate immune response is insufficient to control an infection. In fact, without information from the innate immune system, the adaptive response could not be mobilized. There are two types of adaptive responses: the cell-mediated immune response, which is carried out by T cells, and the humoral immune response, which is controlled by activated B cells and antibodies.
introduction of adaptive immunity. classification of adaptive immunity, factor affecting it and mechanism of adaptive immunity comparison between adaptive immunity and innate immunity. characteristic of adaptive immunity . cell mediated immune responses immunoglobulins
types of immunoglobulins. functions of immunoglobulins, hypersensitivity reactions
Immune system and immunity ppt by DR.C.P.PRINCEDR.PRINCE C P
┬а
Immunity is the power to resist and overcome infection caused by particular organism.
RESISTANCE EXHIBITED BY THE HOST AGAINST MICROBES AND THEIR PRODUCTS
Innate immunity:тАЬInnateтАЭ because shared by all animals (Pre-existing/ By birth) and Non-specific
Adaptive immunity (Acquired Immunity):Responsive and Specific
The immune system recognizes, attacks, destroys, and remembers each pathogen that enters the body.
The Immune System includes all parts of the body that help in the recognition and destruction of foreign materials.
White blood cells, phagocytes and lymphocytes, bone marrow, lymph nodes, tonsils, thymus, and your spleen are all part of the immune system.
prepared by:
DR.PRINCE C P
HOD & Associate Professor
Department of Microbiology
Mother Theresa Post Graduate & Research Institute of Health Sciences (Government of Puducherry Institution)
Pondicherry
Immunity
Definitions
Components of Immune system
Types
Innate immunity and Mechanism
Adaptive immunity and Mechanism
2. Antigen
Origin of Antigen
Immunogen
3. Antibody- Immunoglobulin
- Structure
- Classification
- Function of each antibody
This ppt contains all the information about the Immunity - Host defences. It is useful for students of the medical field learning Preventive and social medicine, Swasthavritta (Ayurved), and everyone who is interested in knowing about it
Immunity is the balanced state of multicellular organisms having adequate biological defenses to fight infection, disease, or other unwanted biological invasion, while having adequate tolerance to avoid allergy, and autoimmune diseases.
Vaccines (Immunotherapy) along with COVID-19 Overview, Types of Vaccines, Adjuvants, Antigen Uptake Mechanism, COVID-19 Mechanism Of Action, and much more.
The general objectives of involving the public at different stages in the EIA process were considered by a recent European Commission research project (EC, 1999) as given in the table.
European union is composed of several hundred countries including Muslim nations like Turkey, Albania etc. So, if one gets access into nation like Poland or Romania, he gets access throughout Europe.
Objectives of public participation during stages of the EIA process
Formal opportunities for public participation in EIA are defined in legislation. While rights of involvement in many countries are limited to opportunities for viewing and commenting on finalised reports, in principle, public consultation and participation can occur at every stage in the EIA process. The table summarizes the main objectives of public involvement at each stage of the EIA process, including a detailed description of these objectives (EC, 1999).
In brief, literature shows that there are a number of advantages of involving the public early on in the EIA process. If participation does occur early on then interaction between the public, developer and decision-making body should continue throughout the EIA process if the full benefits are to be seen.
Table : Summary of Objectives of Public Involvement in EIA
Stage of EIA process Objectives of public involvement
Screening
Identification of significant impacts
Scoping
тАв Identification of public's interest and values
тАв Identification of priorities for assessment
тАв Encouraging public understanding of the proposed project
Assessment
тАв The public can contribute local knowledge and values to the prediction, evaluation and mitigation of impacts
тАв Improvement in quality and acceptability of EIA report
EIA Report Review
Public contribute to evaluation of quality and acceptability of report
Decision
Public comment on acceptability of project impacts
Monitoring
Public evaluate impacts that occur and support project environmental management process
There is an international agency called Environmental Protection Agency EPA. EPA forms and implements regulations regarding making the environment better.
We are at present in a very critical state as far as the situation of global warming and receding snowcaps in the Antarctica. It has been found that there is a hole in the Ozone layer due to increasing level of pollution throughout the world.
The rising sea-levels are threatening the global community. Moreover, the increasing amount of garbage thrown into the seas is a major problem now for countries like Canada. How to manage this sort of problems is equally challenging in both the developed and underdeveloped nations.
6. Solution mitigation of climate change.pptxNeeraj Ojha
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There is an international agency called Environmental Protection Agency EPA. EPA forms and implements regulations regarding making the environment better.
We are at present in a very critical state as far as the situation of global warming and receding snowcaps in the Antarctia. It has been found that there is a hole in the Ozone layer due to increasing level of pollution throughout the world.
5.Climate change and its impact on environment.pptxNeeraj Ojha
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There is an international agency called Environmental Protection Agency EPA. EPA forms and implements regulations regarding making the environment better.
We are at present in a very critical state as far as the situation of global warming and receding snowcaps in the Antarctia. It has been found that there is a hole in the Ozone layer due to increasing level of pollution throughout the world.
4BDirect and indirect health effects of climate change.pptxNeeraj Ojha
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As far as Nepalese people are concerned, they are very bad in their food habits. Disease like ulcer and diabetes are rampant along Nepalese people. Moreover, there are areas in the country where there is a severe malnutrition.
Factors influencing food habits
тАвIndividual Preferences
Every individual has unique likes and dislikes concerning foods.
тАвCultural Influences
A cultural group provides guidelines regarding acceptable foods, food combinations, eating patterns, and eating behaviors.
тАвSocial Influences
Members of asocial group depend on each other, share a common culture, and influence each other's behaviors and values.
As far as Nepalese people are concerned, they are very bad in their food habits. Disease like ulcer and diabetes are rampant along Nepalese people. Moreover, there are areas in the country where there is a severe malnutrition.
Factors influencing food habits
тАвIndividual Preferences
Every individual has unique likes and dislikes concerning foods.
тАвCultural Influences
A cultural group provides guidelines regarding acceptable foods, food combinations, eating patterns, and eating behaviors.
тАвSocial Influences
Members of asocial group depend on each other, share a common culture, and influence each other's behaviors and values.
2,3 Greenhouse gases, global scenario, green house effectt and global warming...Neeraj Ojha
┬а
As far as Nepalese people are concerned, they are very bad in their food habits. Disease like ulcer and diabetes are rampant along Nepalese people. Moreover, there are areas in the country where there is a severe malnutrition.
Factors influencing food habits
тАвIndividual Preferences
Every individual has unique likes and dislikes concerning foods.
тАвCultural Influences
A cultural group provides guidelines regarding acceptable foods, food combinations, eating patterns, and eating behaviors.
тАвSocial Influences
Members of asocial group depend on each other, share a common culture, and influence each other's behaviors and values.
8.1Determinants of Adaptive Capacity.pptxNeeraj Ojha
┬а
There is an international agency called Environmental Protection Agency EPA. EPA forms and implements regulations regarding making the environment better.
We are at present in a very critical state as far as the situation of global warming and receding snowcaps in the Antarctia. It has been found that there is a hole in the Ozone layer due to increasing level of pollution throughout the world.
The rising sea-levels are threatening the global community. Moreover, the increasing amount of garbages thrown into the seas is a major problem now for countries like Canada. How to manage this sort of problems is equally challenging in both the developed and underdeveloped nations.
There is an international agency called Environmental Protection Agency EPA. EPA forms and implements regulations regarding making the environment better.
We are at present in a very critical state as far as the situation of global warming and receding snowcaps in the Antarctia. It has been found that there is a hole in the Ozone layer due to increasing level of pollution throughout the world.
The rising sea-levels are threatening the global community. Moreover, the increasing amount of garbages thrown into the seas is a major problem now for countries like Canada. How to manage this sort of problems is equally challenging in both the developed and underdeveloped nations.
4A Socio-economic and environmental impacts of climate change.pptxNeeraj Ojha
┬а
As far as Nepalese people are concerned, they are very bad in their food habits. Disease like ulcer and diabetes are rampant along Nepalese people. Moreover, there are areas in the country where there is a severe malnutrition.
Factors influencing food habits
тАвIndividual Preferences
Every individual has unique likes and dislikes concerning foods.
тАвCultural Influences
A cultural group provides guidelines regarding acceptable foods, food combinations, eating patterns, and eating behaviors.
тАвSocial Influences
Members of asocial group depend on each other, share a common culture, and influence each other's behaviors and values.
Eating disorders are complex, bio-psycho-social conditions, with multiple causes. Eating disorders arise from a combination of established social, psychological, biological, and interpersonal factors. While they may begin with preoccupations with food and weight, they are most often about much more than food. It is important to understand that the factors that contribute to eating disorders are complex and multifaceted; they are not simply about weight and they are certainly not choices.
PHG 481 Traditional Systems of Medicine BPHARM syllabus PUNeeraj Ojha
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Traditional system of Medicine includes Chinese medicine, Ayurveda, Tibetan medicine, Kampo, Homeopathy etc. Answers are derived from teacher's notes and internet
Pht 402 Clinical Pharmacy questions answered OLD IS GOLDNeeraj Ojha
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These Q/A's are based upon the syllabus by Pokhara University based in the city of Pokhara, Nepal. Hope this will be helpful to the beginners in the schools of pharmacy.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
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i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
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As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health DepartmentтАЩs official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
micro teaching on communication m.sc nursing.pdfAnurag Sharma
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Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
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- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
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Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? тАУ The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
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Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, GanongтАЩs Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, GanongтАЩs Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
2. Innate immunity or nonspecific,
immunity is the natural resistance with
which a person is born. It provides
resistance through several physical,
chemical, and cellular approaches.
Microbes first encounter the epithelial
layers, physical barriers that line our skin
and mucous membranes.
2
3. Immunity
Immunity is defined as the state of resistance or in
susceptibility exhibited by the host to toxic
molecules,micro organisms and foreign cells.
Types of immunity: two types of immunity
1. Non-specific immunity or innate or natural immunity
2. Specific, acquired or adaptive immunity.
3
4. Types of immunity:
1.Species immunity
2.Racial immunity
3.Individual immunity
Host factors in innate immunity
a.Age
b.Hormonal influence
c.Nutrition
4
5. Species immunity
тАв Resistance to infection varies with the species
of animals.
тАв Animals of same species exhibited uniform
pattern of susceptibility to infections.
тАв For eg;disease of mammals do not effect fish
or reptiles and vice versa,Birds are immune to
tetanus.
5
6. Racial immunity
тАв Various animal and plant races show marked
differences in their resistance to certain
infectious disease.
тАв For eg:Algerian race of sheep are immune to
anthrax eventhough which is more common
disease among other races of sheep;Blacks
show high resistance to yellow fever and
malaria than white.
6
7. Individual immunity
тАв Factors affecting in individual immunity
тАв AGE:is an important indicator ,foetus and old
person are more susceptible to any diseases.In
foetus immune cells are immature and in old age
there is gradual wanning of immune cells.
тАв Hormonal influence:Hormonal imbalance are also
responsible for the susceptibility of an individual
to any disease.For eg;diabetes,hypothyroidism
and adrenal dysfunction influence the individuals
susceptibility to infection.
7
8. тАв Nutrition:Immune response is suppressed in
protein malnutrition and is deficiency of some
essential amino acids.Besides this other
factors such as personal hygiene,the nature of
work place and its hazards,the oppurtunity for
contacts with infected individual can also ply
an imp role in innate immunity.
8
9. Adaptive immunity is often sub-divided into two major types
depending on how the immunity was introduced. Naturally
acquired immunity occurs through contact with a disease
causing agent, when the contact was not deliberate, whereas
artificially acquired immunity develops only through
deliberate actions such as vaccination. Both naturally and
artificially acquired immunity can be further subdivided
depending on whether immunity is induced in the host or
passively transferred from a immune host. Passive immunity
is acquired through transfer of antibodies or activated T-cells
from an immune host, and is short lived -- usually lasting only
a few months -- whereas active immunity is induced in the
host itself by antigen, and lasts much longer, sometimes life-
long. The diagram below summarizes these divisions of
immunity.
9
11. Adaptive and innate immunity
тАв The immune system is typically divided into two
categories--innate and adaptive--although these
distinctions are not mutually exclusive.
тАв Innate immunity
тАУ Innate immunity refers to nonspecific defense
mechanisms that come into play immediately or
within hours of an antigen's appearance in the body
тАУ These mechanisms include physical barriers such as
skin, chemicals in the blood, and immune system cells
that attack foreign cells in the body
тАУ The innate immune response is activated by chemical
properties of the antigen
11
12. Adaptive and innate immunity
тАв Adaptive immunity
тАУ Adaptive immunity refers to antigen-specific immune
response
тАУ The adaptive immune response is more complex than
the innate
тАУ The antigen first must be processed and recognized.
Once an antigen has been recognized, the adaptive
immune system creates an army of immune cells
specifically designed to attack that antigen
тАУ Adaptive immunity also includes a "memory" that
makes future responses against a specific antigen
more efficient.
12
13. Types of Acquired Immunity
I. Naturally Acquired Immunity: Obtained in the course
of daily life.
A. Naturally Acquired Active Immunity:
тАУ Antigens or pathogens enter body naturally.
тАУ Body generates an immune response to antigens.
тАУ Immunity may be lifelong (chickenpox or mumps)
or temporary (influenza or intestinal infections).
B. Naturally Acquired Passive Immunity:
тАУ Antibodies pass from mother to fetus via placenta
or breast feeding (colostrum).
тАУ No immune response to antigens.
тАУ Immunity is usually short-lived (weeks to months).
тАУ Protection until childтАЩs immune system develops.
13
14. Types of Acquired Immunity (Continued)
II. Artificially Acquired Immunity: Obtained by
receiving a vaccine or immune serum.
1. Artificially Acquired Active Immunity:
тАУ Antigens are introduced in vaccines
(immunization).
тАУ Body generates an immune response to antigens.
тАУ Immunity can be lifelong (oral polio vaccine) or
temporary (tetanus toxoid).
2. Artificially Acquired Passive Immunity:
тАУ Preformed antibodies (antiserum) are introduced
into body by injection.
тАв Snake antivenom injection from horses or
rabbits.
тАУ Immunity is short lived (half life three weeks).
тАУ Host immune system does not respond to antigens.
14
15. Adaptive and innate immunity
Components of the immune system
Innate immune system Adaptive immune system
Response is non-specific
Pathogen and antigen specific
response
Exposure leads to immediate
maximal response
Lag time between exposure
and maximal response
Cell-mediated and humoral
components
Cell-mediated and humoral
components
No immunological memory
Exposure leads to
immunological memory
Found in nearly all forms of life
Found only in jawed
vertebrates
15
18. Innate immunity
тАв This prevents entry of micro-organisms into tissues or, once they have
gained entry, eliminates them prior to the occurrence of disease
тАв Characteristics
тАУ Present from birth.
тАУ Non-specific - acts on many organisms and does not show specificity.
тАУ Does not become more efficient on subsequent exposure to same
organisms.
тАв Prevention of entry of organisms
тАУ Mechanical barriers at body surfaces, skin, mucous membranes -
disruption leads to infection.
тАУ Antibacterial substances in secretions, lysozyme, lactoferrin, low pH
of stomach contents
тАУ Prevention of stasis.
тАв Peristalsis/flow of urine/upward movement of secretions in
bronchial tree.
тАв Coughing
тАв Vomiting
18
20. Innate immunity
тАв Non-specific elimination of micro-organisms
1. Phagocytosis - ingestion and killing of micro-organisms
by specialised cells (phagocytes)
Phagocytes - polymorphonuclear leukocytes (neutrophils),
mononuclear phagocytes (monocytes, macrophages)
2. Opsonisation - the process of coating micro-organisms
with some of the proteins found in plasma, to make
them more easily phagocytosable
1. An OPSONIN is a plasma protein binding to bacteria. This
promotes adhesion between the opsonised bacteria and
macrophages because the opsonin binds to receptors on
phagocyte membrane e.g. complement with complement
receptors and phagocytes. Opsonisation and phagocytosis
are more efficient in immune individuals.
20
22. Adaptive immunity
тАв It has been observed that the immune system responds to
micro-organisms but not to its own cells and that the system
knows that the body has been infected previously with a
particular organism. This implies:
тАУ Immunological recognition
тАУ Self/non-self discrimination
тАУ Immunological specificity
тАУ Immunological memory
тАв Immunity is mediated by the IMMUNE SYSTEM, which
responds to infection by mounting an IMMUNE RESPONSE. An
immune response must:
тАУ RECOGNISE a micro-organism as foreign (non-self) as distinct from self
тАУ RESPOND to a micro-organism by production of specific antibodies
and specific lymphocytes
тАУ MEDIATE the elimination of micro-organisms
тАУ An agent which evokes an immune response is called
an IMMUNOGEN. The term ANTIGEN is applied to a substance which
reacts with antibody.
22
23. Key mediators of immunity
тАв A specialized group of cells termed as antigen-
presenting cells (APCs) link the innate and adaptive
immune systems by producing cytokines, which:
тАУ Enhance innate immune cell function; and
тАУ Contribute to lymphocyte function
тАв Phagocytes and lymphocytes are key mediators of
immunity
тАв Phagocytes are first line of defense against infection
тАв Lymphocytes have specialized function and mediate
adaptive immune response
23
24. Antigens
тАв Antigens are molecule recognized by receptors in
lymphocytes
тАв Originally the term antigen was used for any molecule
that induced B cells to produce a specific antibody
(antibody generator)
тАв This term now more widely used to indicate molecules
that are specifically recognized by antigen receptors of
either B cells or T cells
тАв So now broadly defined as molecules that initiate
adaptive immune responses (e.g. components of
pathogenic organisms); can also be called immunogen
тАв A large variety of self molecules can serve as antigen
molecule as well, provoking autoimmune responses that
can be highly damaging, and even lethal
24
25. Antigens
тАв Antigens are the initiators and driving forces of all
adaptive immune responses
тАв When antigen is eliminated, immune responses
switch off
тАв Both T cell receptors and immunoglobulin
molecules (antibody) bind to their respective
antigens with a high degree of specificity
тАв They have similar structural relationships and are
closely related in their evolution, but bind to very
different types of antigens and carry out different
biological functions
25
26. Antigens
Epitope:
яБ╡Small part of an antigen that interacts with
an antibody.
яБ╡Any given antigen may have several
epitopes.
яБ╡Each epitope is recognized by a different
antibody.
26
28. Antibody
тАв Soluble antibodies (immunoglobulins) are a group of serum
molecules closely related to and derived from antigen
receptors and B cells
тАв Basic Y-shaped structure with two regions (variable region)
at tip of Y that binds with antigen
тАв Stem of Y is called constant region and is not involved in
antigen binding
тАв The two variable region contains identical antigen binding
sites that are specific to only one type of antigen
тАв However the amino acid sequence in variable region of
different antibodies are extremely variable, therefore
provide an extremely large stock of antigen-binding sites
28
30. Antibody
тАв Pathogens typically have many different antigens
on their surface
тАв Each antibody binds to an epitope, which is a
restricted part of an antigen
тАв A particular antigen can have several different
epitopes or repeated epitopes
тАв Antibodies are specific to epitopes rather than
the whole antigen molecule
тАв The constant region of antibody (Fc region) acts
as adapters to link phagocytes to pathogens
30
32. Immune responses
тАв There are two phases of immune response тАУ antigen
recognition and antigen eradication
тАв Most immune responses to infectious organisms are
made up of a variety of innate and adaptive
components:
тАУ In the earliest stages of infection, innate responses
predominate
тАУ Later the lymphocytes start to generate adaptive immune
responses;
тАУ After recovery, immunological memory remains within the
population of lymphocytes, which can then mount a more
effective and rapid responses if there is a reinfection from
same pathogen later
32
33. Antigen recognition
тАв Lymphocytes are responsible for antigen recognition, and
this is achieved by clonal selection
тАв Each lymphocyte is genetically programmed to be
capable of recognizing just one particular antigen but as
a whole immune system can recognize many thousands
of antigens collectively (collective proportion of specific
lymphocytes)
тАв When an antigen binds to few lymphocytes that can
recognize it , they are induced to proliferate rapidly
which results in sufficient number of lymphocytes to
mount an adequate immune response
тАв Clonal selection тАУ antigen selects and activates the
specific clones to which it binds; this operates for both B
and T cells 33
35. Antigen recognition
тАв Lymphocytes that have been stimulated by binding to
their specific antigen, take the first step towards cell
division
тАУ They express new receptors that allow them to respond to
cytokines from other cells, which signal proliferation
тАУ May start to secrete cytokines themselves
тАУ Will usually go through a number of cycles of division
before differentiating into mature cells under the influence
of cytokines
тАв Memory cells тАУ even when infection has been
overcome, some of the newly produced lymphocytes
remain, available for restimulation if antigen is ever
encountered again; these cells are called memory cells
and can provide immunity to the infection later when
needed
35
36. Antigen eradication
тАв The defense mechanisms by which immune
system can destroy pathogens, each being
suited to given type of infection at a particular
stage of its lifecycle, are often referred to as
effector systems
1. Antibody binding
2. Phagocytosis
3. Cytotoxic reactions
36
37. Effector system
тАв Antibody binding
тАУ One of the simplest effector systems
тАУ Antibodies can combat certain pathogens just by
binding to them
тАУ E.g. antibody to the outer coat proteins of some
rhinovirus (which causes colds) can prevent the
viral particles from binding to and infecting host
cells
37
38. Effector system
тАв Phagocytosis
тАУ Antibodies activates complement or acts as an
opsonin to promote ingestion by phagocytes
тАУ Phagocytes that have bound to an opsonized microbe
engulf it by extending pseudopodia around it
тАУ These fuse and internalize microorganism
(endocytosed)in a phagosome
тАУ Granules and lysosomes fuse with the phagosone,
pouring enzyme into resulting phagolysosome, to
digest the contents
38
40. Effector systems
тАв Cytotoxic reactions
тАУ These are directed against whole cells which are too
large for phagocytosis
тАУ The target cell may be recognized either by
тАв specific antibody bound to the cell surface
тАв T cells using their specific TCRs
тАУ The attacking cells direct their granules towards the
target cell which are discharged into extracellular
space close to the target cells
тАУ These granules contain perforin molecules which can
punch holes in outer membrane of the target
тАУ Some cytotoxic cells can signal to the target cell to
initiate programmed cell death or cell suicide тАУ a
process called apoptosis
40
42. Immune responses to extracellular and intracellular
pathogens
тАв In dealing with extracellular pathogens, the immune
system aims to destroy the pathogen itself and
neutralize its products
тАв In dealing with intracellular pathogens, the immune
system has two functions
тАУ T cells can destroy the infected cells (i.e. cytotoxicity)
тАУ T cells can activate the infected cells to deal with the
pathogen itself (e.g. helper T cells release cytokines, which
activate macrophages to destroy the organisms they have
internalized)
тАв Many pathogens have both intracellular and
extracellular phases of infection, so different
mechanisms are usually effective at different times
42
44. Immune responses to extracellular and intracellular
pathogens
тАв For example, the polio virus travels from the gut,
through the blood stream to infect nerve cells in the
spinal cord
тАв Antibodies and complement can block the extracellular
phase of the life cycle and promote phagocytosis of the
virus
тАв Interferons produced by infected cells signal uninfected
cells to induce state of antiviral resistance
тАв Virus can multiply only within living cells; CTLs
(cytotoxic T lymphocytes) recognize and destroy the
infected cells
44
45. Reference
тАв Roitt, I., Brostoff, J., Male, D. Immunology.
1993. Mosby-Year Book Europe Limited,
London. 3rd Ed.
45