IMMUNITY
Concepts
(Immunity, antigens, antibodies, antigen
antibody reactions, vaccines)
Dr. Ashish V. Jawarkar
M.D.
INFECTION
Relationship between host and
infectious agent
 Saprophytes – live on dead tissue – do not
cause diseases
 Parasites – m...
Infection
 Lodging of parasite in tissues of host
 This is not necessarily disease
Disease
 Any deviation from good health
Infectious disease
 Any deviation from good health due to
infectious agent
Infection
 Primary infection – in healthy host
 Re-infection – repeat infection by the
same agent
 Secondary infection ...
Infection
 Acute – rapid progress
 typhoid
 Chronic – slow onset and progress
 tuberculosis
Infection
 Localised – restricted to specific area
 Systemic
Infection
 Clinical – with symptoms
 Subclinical – no obvious symptoms
Infection
 Oppurtunistic – when host resistance is
lowered
 Nosocomial – acquired from hospital, not
present on admissio...
Sources of infection
 Humans – carriers
 Animals – zoonoses
 Insects
 Soil and water
 Food
Methods of transmission
 Contact – direct, indirect, sexual
 Inhalation
 Ingestion
 Inoculation
 Insects
 Congenital...
Pathogenicity
 Capacity of micro organisms to cause
diseases
Virulence
 Degree of pathogenicity
Factors predisposing to
pathogenicity
 Adhesion – attachment due to receptors
and ligands
Factors predisposing to
pathogenicity
 Invasiveness
 Highly invasive – septicemia following wound
infection by streptoco...
Factors predisposing to
pathogenicity
 Toxins
 Exo toxins – released outside
 Endotoxins – LPS (part of cell wall)
Factors predisposing to
pathogenicity
 Communicability
 Ability to spread from one host to other
 Ensures survival
Types of infectious diseases
 Endemic – constantly present in a
particular area
 Eg typhoid
 Epidemic – one that spread...
IMMUNITY
Immunity
 Resistance exhibited by host towards
micro organisms
Types of immunity
 Innate
 Immunity that a person possesses due to
genetic make up
 Acquired
 Active
• Acquired after ...
Innate immunity Epithelial surfaces
 Skin
 Mucosa
 Saliva
 Urine
 Antibacterial systems in blood and tissues
 Compl...
Acquired (Active)
 Due to stimulation by an antigen (like
microorganism)
 Long lasting
 Associated with memory
Active immunity
 Natural active
 Clinical or subclinical infection
 Eg chicken pox
 Artificial active
 vaccines
Passive immunity
 Natural passive
 Placenta
 Breast milk
 Artificial passive
 Rh iso immunisation
HERD IMMUNITY
 Overall level of immunity in a community
 Useful in case of epidemics
OVERVIEW OF STRUCTURE AND
FUNCTION OF IMMUNE SYSTEM
Lymphocytes
 B lymphocytes – produce antibodies –
Humoral immunity
 T lymphocytes – cell mediated immunity
T cell maturation
(central lymphoid organs)
Central lymphoid organs
 Bone marrow
 Thymus
B cell maturation
(Peripheral lymphoid organs)
Peripheral lymphoid organs
 Lymph nodes
 Spleen
 Mucosa associated lymphoid tissue
(MALT)
 Tonsils
 Peyer’s patches
Other cells of the immune system
 ANTIGEN PRESENTING CELLS (APCs)
Phagocytes (macrophages)
Dendritic cells
eg Langerhan’s cell
MAJOR HISTOCOMPATIBILITY
COMPLEX (MHC)
 Differentiates between self and foreign
ANTIGENS AND ANTIBODIES
ANTIGEN
 Any substance which, when introduced
into the body stimulates production of
antibody
ANTIBODY
 Substance that is produced by the body
against the antigen is an antibody
 It is a protein
 Almost 25% of our...
Types of antigens
 Xenoantigens – from different species
 Alloantigens – from same species
 Autoantigen – lens protein,...
Antigens – on the basis of ability to
cause disease
 Immunogen – develop undesired response
– transplants
 Tolerogens – ...
Biological classes of antigens
 T cell dependent
 T cell independent
Antibodies - types
 Ig G
 Ig A
 Ig M
 Ig D
 Ig E
Structure
IgG
 Can be transported across placenta,
provides immunity to new born
 Neutralize viruses
 Encourage phagocytosis
IgA
 Main immunoglobulin in mother’s milk,
saliva and tears
 Called secretory Ig
 Local immunity
IgM
 Earliest Ig to be synthesized by fetus
 Not transported across placenta
 Presence useful in diagnosis of congenita...
IgD
 Occur on the surface of B lymphocytes
(with IgM) and act as receptors for
antigens
IgE
 On mast cells and basophils
 Responsible for anaphylaxis
(hypersensitivity)
In short
 IgG - protects body fluids
 IgA – protects body surfaces
 IgM – protects the blood stream
 IgD – receptor on...
Antigen – Antibody reactions
 Antigen and antibody can react and cause
 Precipitation
 Agglutination
 Lysis
 Killing ...
Precipitation
Agglutination
Lysis
Killing of microorganisms
General features of antigen –
antibody reaction
 Reaction is specific
 Combination occurs at surface – so
surface antige...
Combinations occur at surface
Combination is reversible
 Affinity – intensity of attraction
 Avidity – strength of bond
 Combine in variable proportions
Applications
 Precipitation reactions
 Agglutination reactions
 Complement fixation tests
 Neutralization tests
 Labe...
Precipitation reactions
 Precipitation – when a soluble antigen
combines with its antibody – antigen
antibody complex for...
Prozone
 Ring test – to group streptococci
 Slide test – VDRL for syphilis
 Tube test – Widal test
Agglutination reactions
 For blood grouping
Labelled immunoassays
Radio immuno assay
ELISA
 HIV
HYPERSENSITIVITY
REACTIONS
(ALLERGY)
.
Definition
• Hypersensitivity – exaggerated immune
response
• Allergen – substance which causes
hypersensitivity
• Hypersensitivity reaction occurs after
second exposure to antigen
• First exposure causes sensitisation
Types
• Based on time between second exposure
and clinical reaction –
– Immediate hypersensitivity
– Delayed hypersensitiv...
Types
• Type I – anaphylactic
• Type II – cytotoxic
• Type III – immune complex
• Type IV – delayed type
Type I hypersensitivity (Allergy)
• a/k/a anaphylaxis (ana – without, phylaxis
– protection)
degranulation
• Releases histamine, serotonin, cytokines
and prostaglandins
• These cause
– Smooth muscle contraction (lar...
• Systemic anaphylaxis is fatal within
minutes
• Unless given adrenaline immediately
allergens
• Nuts
• Seafood
• Eggs
• Insect venom
• Drugs
Atopy
• Anaphylaxis in a localised area
• Eg asthma, hay fever
• Allergens here include
– Dust
– Pollen
– Eggs
– milk
TYPE II HS
• Mediated by IgG or IgM (with complement)
antibodies
• Examples are autoimmune hemolytic
anemias and hemolytic...
Type III HS
• Complexes of antigen and antibody get
deposited in various sites of the body like
– Kidneys
– Joints
– Skin
...
• Examples
– Vasculitis
– Arthus reaction
– Serum sickness
Type IV HS
• Take 2-3 days to occur
• Delayed HS
• Mediated by T cells – antibodies not
involved
• Examples
– Tuberculin r...
Tuberculin reaction
(Montaux test)
• To know whether the person is infected by
TB
• Injection of PPD into skin
• Look for ...
Contact dermatitis
• Skin reaction caused by application of
various chemicals such as nickel,
chromium, drugs such as peni...
Contact dermatitis
Granulomatous reactions
• Occur due to intracellular pathogens such
as Mycobacteria, fungi and Leishmania
• Phagocytes are...
Summary
VACCINES AND
IMMUNISATION
Immunising agents
• Vaccines (active – slower, long lasting)
• Immunoglobulins (passive – faster, short
lasting)
Vaccine
• Substance designed to induce production
of antibodies against a specific disease
causing organism
Types
• Live – live but attenuated organisms
– Eg BCG, oral typhoid vaccine, oral polio
vaccine
• Killed – typhoid, choler...
Immunoglobulins (Passive)
• Administering directly antibodies
• Newborns receive passive immunisation
from colostrum
• Eg ...
Vaccines available
Herd immunity
Contact immunity
• Children immunised with live OPV shed
virus in feces
• An unimmunised family member /
community member ...
National immunisation schedule
(Indian academiy of Paediatrics)
Optional immunisation
• Chicken pox
• Influenzae
• HPV
• Yellow fever
• Japanese encephalitis
• Pneumococcal vaccine
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines
Upcoming SlideShare
Loading in...5
×

Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines

969

Published on

This is a series of lectures on microbiology useful for undergraduate medical and paramedical students

Published in: Health & Medicine, Technology
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
969
On Slideshare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
134
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide

Immunity - concepts - antigen, antibody, ag-ab reactions, vaccines

  1. 1. IMMUNITY Concepts (Immunity, antigens, antibodies, antigen antibody reactions, vaccines) Dr. Ashish V. Jawarkar M.D.
  2. 2. INFECTION
  3. 3. Relationship between host and infectious agent  Saprophytes – live on dead tissue – do not cause diseases  Parasites – multiply in hosts  Pathogens – cause diseases  Commensals – donot cause diseases normally – only during immunosuppression
  4. 4. Infection  Lodging of parasite in tissues of host  This is not necessarily disease
  5. 5. Disease  Any deviation from good health
  6. 6. Infectious disease  Any deviation from good health due to infectious agent
  7. 7. Infection  Primary infection – in healthy host  Re-infection – repeat infection by the same agent  Secondary infection – second infection by a new agent
  8. 8. Infection  Acute – rapid progress  typhoid  Chronic – slow onset and progress  tuberculosis
  9. 9. Infection  Localised – restricted to specific area  Systemic
  10. 10. Infection  Clinical – with symptoms  Subclinical – no obvious symptoms
  11. 11. Infection  Oppurtunistic – when host resistance is lowered  Nosocomial – acquired from hospital, not present on admission  Laboratory acquired – from laboratory
  12. 12. Sources of infection  Humans – carriers  Animals – zoonoses  Insects  Soil and water  Food
  13. 13. Methods of transmission  Contact – direct, indirect, sexual  Inhalation  Ingestion  Inoculation  Insects  Congenital – vertical  Iatrogenic
  14. 14. Pathogenicity  Capacity of micro organisms to cause diseases
  15. 15. Virulence  Degree of pathogenicity
  16. 16. Factors predisposing to pathogenicity  Adhesion – attachment due to receptors and ligands
  17. 17. Factors predisposing to pathogenicity  Invasiveness  Highly invasive – septicemia following wound infection by streptococci  Less invasive – staphylococcal abscess
  18. 18. Factors predisposing to pathogenicity  Toxins  Exo toxins – released outside  Endotoxins – LPS (part of cell wall)
  19. 19. Factors predisposing to pathogenicity  Communicability  Ability to spread from one host to other  Ensures survival
  20. 20. Types of infectious diseases  Endemic – constantly present in a particular area  Eg typhoid  Epidemic – one that spreads rapidly involving many persons at the same time  influenza  Pandemic – spreads through many areas of the world at the same time
  21. 21. IMMUNITY
  22. 22. Immunity  Resistance exhibited by host towards micro organisms
  23. 23. Types of immunity  Innate  Immunity that a person possesses due to genetic make up  Acquired  Active • Acquired after an exposure to infection (natural) / artificially induced (vaccine)  Passive • Injection of antibodies
  24. 24. Innate immunity Epithelial surfaces  Skin  Mucosa  Saliva  Urine  Antibacterial systems in blood and tissues  Complement system  Interferons  Microbial antagonism  Flora  Cells  macrophages  Neutrophils  NK cells  Inflammation  Fever  Acute phase proteins  CRP
  25. 25. Acquired (Active)  Due to stimulation by an antigen (like microorganism)  Long lasting  Associated with memory
  26. 26. Active immunity  Natural active  Clinical or subclinical infection  Eg chicken pox  Artificial active  vaccines
  27. 27. Passive immunity  Natural passive  Placenta  Breast milk  Artificial passive  Rh iso immunisation
  28. 28. HERD IMMUNITY  Overall level of immunity in a community  Useful in case of epidemics
  29. 29. OVERVIEW OF STRUCTURE AND FUNCTION OF IMMUNE SYSTEM
  30. 30. Lymphocytes  B lymphocytes – produce antibodies – Humoral immunity  T lymphocytes – cell mediated immunity
  31. 31. T cell maturation (central lymphoid organs)
  32. 32. Central lymphoid organs  Bone marrow  Thymus
  33. 33. B cell maturation (Peripheral lymphoid organs)
  34. 34. Peripheral lymphoid organs  Lymph nodes  Spleen  Mucosa associated lymphoid tissue (MALT)  Tonsils  Peyer’s patches
  35. 35. Other cells of the immune system  ANTIGEN PRESENTING CELLS (APCs)
  36. 36. Phagocytes (macrophages)
  37. 37. Dendritic cells eg Langerhan’s cell
  38. 38. MAJOR HISTOCOMPATIBILITY COMPLEX (MHC)  Differentiates between self and foreign
  39. 39. ANTIGENS AND ANTIBODIES
  40. 40. ANTIGEN  Any substance which, when introduced into the body stimulates production of antibody
  41. 41. ANTIBODY  Substance that is produced by the body against the antigen is an antibody  It is a protein  Almost 25% of our body proteins are Immunoglobulins
  42. 42. Types of antigens  Xenoantigens – from different species  Alloantigens – from same species  Autoantigen – lens protein, testis  Heterophile antigen – closely related antigens from different species
  43. 43. Antigens – on the basis of ability to cause disease  Immunogen – develop undesired response – transplants  Tolerogens – induce immunological tolerance due to memory  Allergens – over reactions  Vaccines – protective response
  44. 44. Biological classes of antigens  T cell dependent  T cell independent
  45. 45. Antibodies - types  Ig G  Ig A  Ig M  Ig D  Ig E
  46. 46. Structure
  47. 47. IgG  Can be transported across placenta, provides immunity to new born  Neutralize viruses  Encourage phagocytosis
  48. 48. IgA  Main immunoglobulin in mother’s milk, saliva and tears  Called secretory Ig  Local immunity
  49. 49. IgM  Earliest Ig to be synthesized by fetus  Not transported across placenta  Presence useful in diagnosis of congenital infections such as syphilis, rubella, HIV and toxoplasmosis  Responsible for protection from blood invasion by microorganisms
  50. 50. IgD  Occur on the surface of B lymphocytes (with IgM) and act as receptors for antigens
  51. 51. IgE  On mast cells and basophils  Responsible for anaphylaxis (hypersensitivity)
  52. 52. In short  IgG - protects body fluids  IgA – protects body surfaces  IgM – protects the blood stream  IgD – receptor on surface of B lymphocytes  IgE – mediates anaphylaxis
  53. 53. Antigen – Antibody reactions  Antigen and antibody can react and cause  Precipitation  Agglutination  Lysis  Killing of live antigens (micro organisms)
  54. 54. Precipitation
  55. 55. Agglutination
  56. 56. Lysis
  57. 57. Killing of microorganisms
  58. 58. General features of antigen – antibody reaction  Reaction is specific  Combination occurs at surface – so surface antigens are relevant  Combination is firm but reversible  Antigen and antibody can combine in variable proportions
  59. 59. Combinations occur at surface
  60. 60. Combination is reversible  Affinity – intensity of attraction
  61. 61.  Avidity – strength of bond
  62. 62.  Combine in variable proportions
  63. 63. Applications  Precipitation reactions  Agglutination reactions  Complement fixation tests  Neutralization tests  Labelled immunoassays  Immunofluorescence  Radio immunoassay  Enzyme linked immunosorbent assay (ELISA)
  64. 64. Precipitation reactions  Precipitation – when a soluble antigen combines with its antibody – antigen antibody complex forms an insoluble ppt in the medium
  65. 65. Prozone
  66. 66.  Ring test – to group streptococci
  67. 67.  Slide test – VDRL for syphilis  Tube test – Widal test
  68. 68. Agglutination reactions  For blood grouping
  69. 69. Labelled immunoassays
  70. 70. Radio immuno assay
  71. 71. ELISA  HIV
  72. 72. HYPERSENSITIVITY REACTIONS (ALLERGY) .
  73. 73. Definition • Hypersensitivity – exaggerated immune response • Allergen – substance which causes hypersensitivity
  74. 74. • Hypersensitivity reaction occurs after second exposure to antigen • First exposure causes sensitisation
  75. 75. Types • Based on time between second exposure and clinical reaction – – Immediate hypersensitivity – Delayed hypersensitivity
  76. 76. Types • Type I – anaphylactic • Type II – cytotoxic • Type III – immune complex • Type IV – delayed type
  77. 77. Type I hypersensitivity (Allergy) • a/k/a anaphylaxis (ana – without, phylaxis – protection)
  78. 78. degranulation • Releases histamine, serotonin, cytokines and prostaglandins • These cause – Smooth muscle contraction (larynx, lungs) – Leaky blood vessels (rhinorrhoea, oral secretions) – Intestinal fluid secretion (diarrhoea and vomitting)
  79. 79. • Systemic anaphylaxis is fatal within minutes • Unless given adrenaline immediately
  80. 80. allergens • Nuts • Seafood • Eggs • Insect venom • Drugs
  81. 81. Atopy • Anaphylaxis in a localised area • Eg asthma, hay fever • Allergens here include – Dust – Pollen – Eggs – milk
  82. 82. TYPE II HS • Mediated by IgG or IgM (with complement) antibodies • Examples are autoimmune hemolytic anemias and hemolytic disease of newborn
  83. 83. Type III HS • Complexes of antigen and antibody get deposited in various sites of the body like – Kidneys – Joints – Skin – Eye
  84. 84. • Examples – Vasculitis – Arthus reaction – Serum sickness
  85. 85. Type IV HS • Take 2-3 days to occur • Delayed HS • Mediated by T cells – antibodies not involved • Examples – Tuberculin reaction – Contact dermatitis
  86. 86. Tuberculin reaction (Montaux test) • To know whether the person is infected by TB • Injection of PPD into skin • Look for raised area (induration) after 48 hours
  87. 87. Contact dermatitis • Skin reaction caused by application of various chemicals such as nickel, chromium, drugs such as penicillin and toiletries.
  88. 88. Contact dermatitis
  89. 89. Granulomatous reactions • Occur due to intracellular pathogens such as Mycobacteria, fungi and Leishmania • Phagocytes are unable to remove and digest them and become giant cells with multiple nuclei
  90. 90. Summary
  91. 91. VACCINES AND IMMUNISATION
  92. 92. Immunising agents • Vaccines (active – slower, long lasting) • Immunoglobulins (passive – faster, short lasting)
  93. 93. Vaccine • Substance designed to induce production of antibodies against a specific disease causing organism
  94. 94. Types • Live – live but attenuated organisms – Eg BCG, oral typhoid vaccine, oral polio vaccine • Killed – typhoid, cholera, injectable polio vaccine • Toxoids - DPT
  95. 95. Immunoglobulins (Passive) • Administering directly antibodies • Newborns receive passive immunisation from colostrum • Eg – Hep B antibodies given after accidental exposure • Protect immunodeficient individuals
  96. 96. Vaccines available
  97. 97. Herd immunity
  98. 98. Contact immunity • Children immunised with live OPV shed virus in feces • An unimmunised family member / community member who is exposed to this shed virus develops immunity as well
  99. 99. National immunisation schedule (Indian academiy of Paediatrics)
  100. 100. Optional immunisation • Chicken pox • Influenzae • HPV • Yellow fever • Japanese encephalitis • Pneumococcal vaccine
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×