Describes the basic properties and mechanisms of T cells and B cells in maintaining Immune Response against foreign antigens or infections and covers the UG and PG portion of immunology.
Humoral immunity is defined as the immunity mediated by antibodies, which are secreted by B lymphocytes.
B lymphocytes secrete the antibodies into the blood and lymph
Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues. Any disease that results from such an aberrant immune response is termed an "autoimmune disease".
Humoral immunity is defined as the immunity mediated by antibodies, which are secreted by B lymphocytes.
B lymphocytes secrete the antibodies into the blood and lymph
Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues. Any disease that results from such an aberrant immune response is termed an "autoimmune disease".
Immune response during bacterial, parasitic and viral infection.pptxVanshikaVarshney5
when a pathogen attacks on our body how's our body react to it?
this presentation is all about that.
How the immune respone to the parasite, virus or bacteria and save our body.
Antigen is substance which when introduced parentally into the body stimulates the production of an antibody with which it reacts specifically and in an observable manner.
CLASSIFICATION OF ANTIGENS
Based on Immunogenicity
Complete antigen : substances with both immunogenicity and immunoreactivity Incomplete antigen
Incomplete antigen ( hapten): substances only with immunoreactivity
Hapten +carrier → complete antigen
( Immunogenicity : induction of immune response
• Immunological Reactivity: specific reaction with antibodies or sensitized cells)
HAPTENS
The term Hapten was given by the immunologist Karl Landsteiner, who studied them in early 20th century.
• It came from a Greek word Haptein meaning to fasten.
DEFINITION OF HAPTENS
Small, non-biologic molecules that bind to immune cells receptors but cannot by themselves induce a specific immune response
That are antigenic but not immunogenic Which means that they can bind to immune cells but fail to induce Humoral or cell mediated immune response. Hence no antibodies are raised against them
HAPTENS
The term Hapten was given by the immunologist Karl Landsteiner, who studied them in early 20th century.
• It came from a Greek word Haptein meaning to fasten.
DEFINITION OF HAPTENS
Small, non-biologic molecules that bind to immune cells receptors but cannot by themselves induce a specific immune response
That are antigenic but not immunogenic Which means that they can bind to immune cells but fail to induce Humoral or cell mediated immune response. Hence no antibodies are raised against them
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
Lymphocyte is a type of white blood cell in the immune system of jawed vertebrate. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity). They are the main type of cell found in lymph, which prompted the name "lymphocyte". Th all myeloid and lymphoid cells develop from one type of stem cell called as Hematopoietic stem cell is a undifferentiated cell give rise to further diffetentiation of all the immune cell as well as blood cells include the T- cell and B-cell. The B-cell is synthesis and matured in the Bone Marrow and T- cell is synthesis in Bone marrow but matured in the thymus. In this topic will be discussed how the B-cell and T-cell are developed
This presentation gives you the detailed description of various cells & organs of immune systems that participates (particularly, in combination), make communication between themselves to regulate the whole immune system very precisely.
A brief covering basics of immunity understanding and also allowing students to understand with ease the concepts of innate immunity, adaptive immunity, Tcell, Bcell, MHC molecular genetics, and also cytokines and also its role in various disease.
Immune response during bacterial, parasitic and viral infection.pptxVanshikaVarshney5
when a pathogen attacks on our body how's our body react to it?
this presentation is all about that.
How the immune respone to the parasite, virus or bacteria and save our body.
Antigen is substance which when introduced parentally into the body stimulates the production of an antibody with which it reacts specifically and in an observable manner.
CLASSIFICATION OF ANTIGENS
Based on Immunogenicity
Complete antigen : substances with both immunogenicity and immunoreactivity Incomplete antigen
Incomplete antigen ( hapten): substances only with immunoreactivity
Hapten +carrier → complete antigen
( Immunogenicity : induction of immune response
• Immunological Reactivity: specific reaction with antibodies or sensitized cells)
HAPTENS
The term Hapten was given by the immunologist Karl Landsteiner, who studied them in early 20th century.
• It came from a Greek word Haptein meaning to fasten.
DEFINITION OF HAPTENS
Small, non-biologic molecules that bind to immune cells receptors but cannot by themselves induce a specific immune response
That are antigenic but not immunogenic Which means that they can bind to immune cells but fail to induce Humoral or cell mediated immune response. Hence no antibodies are raised against them
HAPTENS
The term Hapten was given by the immunologist Karl Landsteiner, who studied them in early 20th century.
• It came from a Greek word Haptein meaning to fasten.
DEFINITION OF HAPTENS
Small, non-biologic molecules that bind to immune cells receptors but cannot by themselves induce a specific immune response
That are antigenic but not immunogenic Which means that they can bind to immune cells but fail to induce Humoral or cell mediated immune response. Hence no antibodies are raised against them
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
Lymphocyte is a type of white blood cell in the immune system of jawed vertebrate. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity). They are the main type of cell found in lymph, which prompted the name "lymphocyte". Th all myeloid and lymphoid cells develop from one type of stem cell called as Hematopoietic stem cell is a undifferentiated cell give rise to further diffetentiation of all the immune cell as well as blood cells include the T- cell and B-cell. The B-cell is synthesis and matured in the Bone Marrow and T- cell is synthesis in Bone marrow but matured in the thymus. In this topic will be discussed how the B-cell and T-cell are developed
This presentation gives you the detailed description of various cells & organs of immune systems that participates (particularly, in combination), make communication between themselves to regulate the whole immune system very precisely.
A brief covering basics of immunity understanding and also allowing students to understand with ease the concepts of innate immunity, adaptive immunity, Tcell, Bcell, MHC molecular genetics, and also cytokines and also its role in various disease.
Difference between humoral and cell mediated immunity Dr. ihsan edan abdulkar...dr.Ihsan alsaimary
Dr. ihsan edan abdulkareem alsaimary
PROFESSOR IN MEDICAL MICROBIOLOGY AND MOLECULAR IMMUNOLOGY
ihsanalsaimary@gmail.com
mobile : 009647801410838
university of basrah - college of medicine - basrah -IRAQ
The immune response is how our body recognizes and defends itself against pathogens like bacteria, viruses, and substances that appear foreign and harmful.
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.
A detailed description of HIV covering virology, morphology, pathogenesis, clinical stages and manifestations, laboratory diagnosis, and diagnostic strategy, and therapeutic options and prevention.
Basic discussion on Coccidian parasites with a focus on Cryptosporidiosis -morphology, life cycle, pathogenesis, clinical manifestations, and laboratory diagnosis and management.
Morphology, Life cycle, Clinical manifestations and laboratory diagnosis of E. histolytica from Clinical and Microbiological point of view for UG and PG Students.
Basic discussion on Clinical and Microbiological Aspects of Food Poisoning caused by various bacteria, viruses, protozoa, and Fungi along with their clinical and laboratory diagnosis and basic management.
Basic description of Infective Endocarditis from a Clinical and Microbiological point of view with description on Pathogenesis, Clinical Manifestations, Clinical and Laboratory diagnosis.
Basic description of Lyme disease from Microbiological and Clinical point of view with discussion on Pathology, Clinical Features and, Laboratory Diagnosis.
A basic description of Leishmania spp. along with Old and New world Leishmaniasis regarding Parasite morphology, Life Cycle, Pathogenesis, Clinical manifestations, Laboratory Diagnosis and Treatment.
Detailed description of malarial parasites especially P. falciparum with regards to their Morphology, Life cycle, Pathogenesis, Epidemiology, Clinical manifestations and complications and Laboratory diagnosis including modern methods and treatment.
Concise discussion on Fialrial worms including Morphology, Life cycle, pathogenesis, clinical manifestations and laboratory diagnosis including newer techniques for UG and PG students.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
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.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
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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, Ganong’s 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
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
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
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
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 Department’s 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
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.
2. Introduction
Immune response refers to the highly coordinated reaction of the cells of the
immune system and their products. It has 2 arms
Humoral or Antibody mediated immune response (AMI)
It provides protection to the host by secreting antibodies that can bind to the
microbial antigens that are circulating or present on the cell surface and
neutralize them.
No role against intracellular antigens.
Cell mediate immunity (CMI)
Crucial role in providing protection against intracellular microbes as well as
tumors.
Although, CMI is mainly T-cell mediated but other components like NK
cells, macrophages, granulocytes are also important.
5. Introduction
CMI and AMI are interdependent-
They don’t work independently but are highly dependent on each other.
Cytokines released from T cells stimulate B-cells to produce antibodies.
Many effector cells of CMI like Macrophages and NK cells use antibodies
to recognize the target cells for killing.
CMI regulates HMI by regulating transformation of B-cells into antibody
secreting plasma cells.
There are certain initial events that takes places before induction of either
CMI or AMI.
These events occur irrespective of the type of immune response that will
follow.
6. Antigen presentation to
Helper T-cells
Activation and Differentiation of
Helper T-cells into TH1 or TH2 subsets
TH1 cells secret
Cytokines CMI
TH2 cells secret Cytokines
HMI
TH1 Cytokines and their functions
IL2
Promotes activation of TH and TC cells.
Activates NK cells to become LAK cells
(Lymphokine
Activated killer cells)
INF-𝜸
Activates the resting macrophages to activated
Macrophages
Activates B cells to produce IgG.
Delayed type of Hypersensitivity.
Inhibits TH2 cell proliferation.
TNF-𝜷
Enhances phagocytic activity of Macrophages.
TH2 Cytokines and their functions
IL-4
Inhibits TH1 cells differentiation.
Stimulates B cells to produce IgE and IgG-1
&4.
IL-5
Enhances the proliferation of Eosinophils.
IL-4&5- protection against Helminthic
Infections and mediate Allergic Reactions.
IL-6
B-cell proliferation and Antibody production
IL-10
Inhibits TH1 differentiation.
7.
8. Interactions between the innate and acquired immune
systems in response to bacterial infection of the skin.
In response to bacteria that have breached the epithelial barrier
Keratinocytes synthesize anti-microbial peptides, chemokines, and
cytokines.
These factors lead to activation of the dermal endothelium, inducing
the migration of innate leukocytes and memory T cells into the skin
and additionally guiding these cells via chemotactic gradients.
These factors and bacterial antigens activate innate phagocytes to kill
ingested organisms and activate dendritic cells to migrate to the
skin-homing lymph nodes.
9. Interactions between the innate and acquired immune
systems in response to bacterial infection of the skin.
In the lymph nodes, dendritic cells present bacterial antigens to
naı¨ve and central memory T cells, leading to stimulation of
pathogen-specific cells.
Effector CD8 cells exit the lymph node, home to inflamed skin and
kill pathogens.
Helper CD4 T cells provide help to B cells, inducing the production
of antibodies that directly neutralize pathogens and lead to additional
targeting of innate responses.
Antibody-directed phagocytosis by innate cells leads to enhanced
antigen presentation, further enhancing acquired responses.
10.
11.
12. Cluster of differentiation in helper T cell
The helper T cells can be Th1, Th2, Th9, Th17, or Th22 cells, depending
upon the pathogen and types of cytokines present in the cellular
microenvironment.
They are responsible for responding to both intracellular as well as
extracellular pathogens and have also been found to be involved in various
diseases.
CD4 T helper (Th) cells play a central role in orchestrating adaptive
immune responses to invading pathogens through their ability to
differentiate into specialized effector subsets.
Part of this customized response requires the development of T follicular
helper (Tfh) cells, which provide help to B cells for the generation of
Germinal Centers (GCs) and long-term protective humoral responses.
13. Cluster of differentiation in helper T cell
CD4 T helper cells are the primary orchestrators of the adaptive
immune response, mediating a variety of cellular and humoral
responses against pathogens and cancer.
Although they lack any capacity to directly kill or engulf pathogens,
they are powerful activators of effector cells such as macrophages,
cytotoxic T cells, and B cells.
On the other hand, Regulatory T cells (Tregs) are potent suppressors
of the immune response important in limiting the immune reaction.
Recent advances have led to the discovery of a diverse set of T helper
subsets, each with unique functions.
17. Antigen Presentation
Antigen Presenting Cells (APCs)
For induction of immune responses, recognition of antigens by T-cells is essential.
T cells can’t recognize the native and free antigens, but can do so only after antigen is
processed into smaller antigenic peptides containing specific epitopes which are
subsequently combined with MHC molecules (Class -1 /2) and presented on the host cell
surface.
Antigen presentation means the presentation of antigenic peptide to both TH (Helper T
cell) and TC (Cytotoxic T cells) by complexing with MHC class 2 and class 1 respectively.
However, APCs in strict sense refers to only only those cells (e.g, Dendritic cells, Macrophages
etc.) that present antigenic peptides to TH cells.
Virus infected cells or Tumor cells presents antigenic peptides to TC cells leading to their
activation and they aren’t considered as APCs rather termed as “Target cells”.
Professional APCs- Dendritic Cells, Macrophages, B-cells.
Non-Professional APCs- Fibroblasts (Skin), Endothelial cells (vessels), Glial cells (Brain).
18. Antigen Presentation
Antigen Presenting Pathways
• For induction of immune response the the antigens must be presented to TH
cells and also to TC cells. Two well defined pathways are used for this
purpose
Cytosolic Pathway-
Here, the endogenous (i.e. Intracellular) antigens such as Viral or tumor
antigens are processed and presented along MHC Class 1 molecules to
CD8 T cells.
Endocytic pathway-
The exogenous antigens (extracellular microbes and their products like
toxins) are processed and complexed with MHC class 2 molecules and
presented to TH Cells.
Professional APCs are mostly involved in this pathway.
19.
20.
21.
22.
23. Cell Mediated Immune Response (CMI)
CMI refers to the destruction of cells carrying intracellular microbes and other
abnormal cells, such as tumor cells by various specific and non-specific cells of
immune system, of which the most important is the cytotoxic T cells.
Role of CMI-
For obligate intracellular organisms like Mycobacteria, Chlamydia, Rickettsia,
plasmodium, leishmania etc. CMI remains the only effective immune response.
For facultative intracellular organisms like Listeria, Salmonella, Yersinia and
Fungi such as Histoplasma and Cryptococcus, CMI becomes the leading immune
response once the organism goes intracellular from extracellular.
Provides immunity against tumor and damaged or altered cells.
Mediates Type-4 Hypersensitivity.
24. Cell Mediated Immune Response (CMI)-
Effector Cells
CMI can be mediated by both Antigen specific and non-specific
effector cells. They perform their function by direct killing of the
target cells.
Antigen specific- Cytotoxic T cells (Most important)
Non-specific – NK Cells, Macrophages, Neutrophils, Eosinophils.
CMI is interdependent on HMI as non specific effector cells use
Antibodies for their killing (ADCC- Antibody Dependent Cell
Mediated Cytotoxicity).
25. T cell stimulation and polarization require
four signals from dendritic cells
26. Signal one determines antigen specificity
and consists of interaction of the T cell receptor
(TCR) with peptides loaded onto dendritic cell
major histocompatibility (MHC) molecules.
Signal two consists of co-signaling and can
be either positive, leading to cell activation (co-
stimulation) or negative, leading to no response
(co-inhibition).
Co-signaling molecules, including CD80 and
CD86, are upregulated on dendritic cells after
binding of pathogen-associated molecular patterns
(PAMP) to their cognate receptors.
27. Signal three involves the polarization of CD4 T cells into either Th1, Th2, or regulatory T cells.
Immature dendritic cells are polarized by the binding of type 1, type 2, or regulatory PAMP and differentiate into
mature dendritic cells that induce the formation of Th1, Th2, or T regulatory T cells, respectively.
In general, viral-associated PAMP give rise to Th1 responses, and PAMP from parasitic organisms favour Th2
responses.
28. Signal four leads to spatial
imprinting of T cells, leading to
the acquisition of homing
receptors that induce selective
recirculation through the tissue in
which antigen was first
encountered.
Dendritic cells from the intestine
uniquely produce retinoic acid,
inducing T cells to upregulate the
T cell gut-homing receptors a4b7
and CCR9 and suppress
expression of the skin-homing
receptor cutaneous lymphocyte
antigen (CLA).
Signals that polarize T cells to
migrate to other sites, including
the skin, brain, and pulmonary
epithelia, have yet to be identified.
29. Natural Killer (NK) Cells
NK cells are large granular lymphocytes that constitutes 10-15% of peripheral blood
lymphocytes, derived from a separate lymphocyte linage.
They are cytotoxic but non-specific.
They are part of innate immunity and don’t require prior contact with antigen.
NK cells act against the virus infected cells and tumor cells till the Tc cells are activated and
take over the function.
NK cells lack the T cell markers like CD3/4/8 (hence also called Null cells), instead they have CD
16& 56.
NK Cells don’t differentiate into memory cells.
Mechanism of NK cells mediated Cytotoxicity-
NK cells directly recognize certain ligands (Glycoproteins) present on the altered cell surface
without the help of MHC molecules.
This is mediated by 2 types of receptor present on NK cell surface (Theory of Opposing Signal
Model)
30. Natural Killer (NK) Cells
Activation receptors- (NKR-P1, CD 16): When these receptors are engaged with
ligands present on target cells, NK cells become activated.
Inhibitory Receptors- (C-type lectin inhibitory receptors)-
They recognize a part of MHC 1 molecules (HLA-E) which is present on all
nucleated cells.
Binding of inhibitory receptor to MHC 1 molecules generates an inhibitory signal
that suppresses NK cells even if they are bound to activation receptors.
However, in target cells, the MHC 1 expression is remarkably reduced. In
such cases there would not be any inhibitory signal NK Cell activation.
Target Cell destruction-
Mechanism of target cell lysis by NK cells and T cells are similar i.e. by secreting
Perforins and Granzymes. Perforins form pores on the target cell through
which granzymes enter and lyse the target cells.
32. Two ways to kill.
(A)Granule-mediated cytotoxicity is initiated by the targeted release of lytic
granules toward a locally attached target cell.
Granzymes can then enter the target cell by perforin-pores in the plasma
membrane (left) or by endocytosis and perforin-aided escape from endosomes
(right).
Granzymes can then induce caspase activation, mitochondrial dysfunction, or
caspase-independent apoptosis.
(B)Death receptor-mediated cytotoxicity is induced by surface expression of
FasL or TRAIL, which can engage and activate their respective receptor.
This results in caspase activation, mitochondrial dysfunction, and apoptosis.
33. Antibody dependent
cell mediated cytotoxicity (ADCC)-
A number of non-specific cytotoxic cells express receptors (FcR) on their
surface that can bind to Fc region of any immunoglobulin.
Following contact with a target cell coated with an antibody, these FcR
bearing cells can bind to Fc portion of the antibody coated on the target
cells, and subsequently cause lysis of the target cells.
Although these cells are non-specific for antigen, the specificity of the
antibody directs them towards the specific target cells. This type of
cytotoxicity is referred to as ADCC.
ADCC is shown by NK Cells, Macrophages, Neutrophils and
Eosinophils.
They release various cytotoxic factors into the target cells like perforins,
Granzymes, Lytic enzymes, free radicals, TNF etc.
34.
35.
36. Humoral/Antibody Mediated
Immune Response (HMI/AMI)
AMI occurs through the following 3 sequential steps
1. Activation of B-cells following contact with microbial antigen (B
cells act as APCs)
2. Proliferation and differentiation of B cells into effector cells
(antibody producing plasma cells) and Memory cells.
3. Effector FunctionProduction of Ab. Neutralization
Opsonization
Complement
activation
37. A] HMI- Activation of B-cells
Antigens that activate B cells fall into 2 categories
A. Most of the antigens are Thymus Dependent (TD):
They activate B cells indirectly via activation of T cells.
Activated TH cells Cytokines Activation of B cells.
B. Thymus independent antigens (TI):
Antigens like bacterial capsule are not processed by APC and directly activate B cells without the
help of T cell cytokines.
Activation of B-cells
The first and foremost step that occurs is the recognition of TD antigen by B cell membrane
immunoglobulin (mIg) receptor receptor mediated endocytosis of antigen.
Then the antigen is processed into smaller antigenic peptides that are presented in complex with
MHC-2 to activate TH cells (Endocytic pathway)
This leads to induction of 3 signals
38. A] HMI- Activation of B-cells
Signal-1: It is inducted by cross linkage of IgM on B cell membrane
with the microbial antigen.
Signal-2 It is an additional signal provided by binding of CD 40 on
B cells with CD40L on activated TH cells.
Signal-3 It is usually Cytokine stimulus due to TH cell produced
cytokines.
Signal Transduction
Following induction of signal, its transmission is essential for B cell
activation and it is initiated by B Cell Receptor (BCR).
39.
40.
41.
42.
43. B] HMI- Proliferation and
Differentiation of B-cells
Naïve B cells released from Bone Marrow B cell areas of peripheral
lymphoid organs (Cortex of lymph node and marginal zone of
spleen.) Primary Lymphoid follicles.
Antigenic exposure Activation of naïve B cells Proliferation.
Primary lymphoid follicles Secondary lymphoid follicles
Germinal Centers
Dark Zone
Light Zone
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45.
46.
47. B] HMI- Proliferation and
Differentiation of B-cells
Events in the Dark Zone of Germinal Center
Activated B cells (differentiate) larger dividing cells –(Centroblasts)
transforms into nondividing cells, Centrocytes.
Centroblasts express membrane Ig by a process k/a Somatic Hypermutation.
This results in alteration of membrane Ig affinity by which it binds to
corresponding antigen.
Because somatic mutations occur randomly, they generate membrane Ig with
both High & Low affinity.
Centrocytes with low affinity undergo Apoptosis Phagocytosed by special
Tingible body Macrophages.
Centrocytes with high affinity Survive and migrate to light zone.
The process of enhancement of Ig for Ag binding is called Affinity maturation.
48.
49.
50. B] HMI- Proliferation and
Differentiation of B-cells
Events in the light zone of Germinal Center
Binding of centrocytes to follicular dendritic cells->
The centrocytes with high affinity Ig undergo maturation by binding to a special type of
dendritic cells (Follicular Dendritic Cells- FDC).
Then the mature dendritic cells undergo class switch over.
Class Switch Over-
Early in the immune response IgM is the predominant immunoglobulin secreted by the B
cells.
But as the maturation progresses the same B cells undergo a phenomenon called CLASS
SWITCHING.
Binding of cytokines produced by TH cells induces Class Switch Over.
Different cytokines induce production of different classes of Ig by switching mechanism.
51. B] HMI- Proliferation and
Differentiation of B-cells
Cytokines Ig Class Produced
INF-𝛾 IgG2a/ IgG3
IL-5 + TGF β IgA/ IgG2b
IL-4 IgE/G1/G4
IL-2,4,5 IgM
IL-4,5,6 +INF-𝛾 IgG
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53.
54. B] HMI- Proliferation and
Differentiation of B-cells
Differentiation of centrocytes into Plasma cells and Memory Cells
After class switching , the selected centrocytes undergo further
differentiation into effector cells (Plasma cells) and Memory cells in
the light zone of germinal center.
Plasma cells are large Ab secreting cells; produce secretory Ig
enormously, but do not have membrane Ig or MHC class-2 molecules.
Memory B cells bear high affinity Ig of all classes as compared to
naïve B cells that only bear low affinity IgM/ IgD membrane Ig.
They are long lived cells which responds to secondary antigenic
stimulus.
55.
56. C] Effector Functions of AMI
Antibodies secreted from plasma cells perform a number of biological
functions.
Promotes Opsonization- FcRs, present on phagocytes surface recognize the
Ab coated microbes Binding Enhanced phagocytosis.
Transcytosis- Movement of Ab via epithelial cells from their basolateral
side to apical side.
Mediates mucosal immunity- This is due to transcytosis of IgA mostly to
gut lumen that neutralizes microbes at local mucosal sites.
Activates complement mediated inflammation and cytolysis
Promotes ADCC.