Immune response

1. Immune Response
K.Kamatchi
Assistant Professor
Department of Zoology
Vivekananda College
Tiruvedakam West

2. •Reaction of organism – foreign body
•Aim to inactivate, destroy, eliminate –
Ag
•Humoral and cell mediated immune
Response.
•HI – act against – Ab
•CMI – activated lymphocytes.

3. Humoral immune response
Destruction of Ag – Ab
Antibody mediated immune response
Ab kill – Ag (pathogens) outside the cells
Can’t kill – Ag inside the cells
Kill and neutralises – Ag and toxins
B cells – B cells mediated immunity. – effector cells
B cell – need – cooperation – T helper cells
IR – entry – Ag – first – Primary Immune response
Primary dose
Same Ag – second time – Secondary immune response
Secondary dose – booster dose.

4. •HI – production of Ab – blood plasma
•Amount – Ab – antibody titre
•Sigmoid curve – immune response curve
•Lag phase
•Log phase
•Plateau phase
•Decline phase

5. Primary Immune Response
Lag phase:
Immediate – infection
No Ab
Latent period or induced period
Several hours – days
Log phase:
Antibody titre rises steadily
Plateau phase:
Ab – stable
Decline phase:
Fall of Ab

6. Secondary Immune Response
Very quickly
Lag phase
Log phase
Plateau phase
Decline phase

7. •B cell activation:
•Stimulation of B cell
•Derived – bone marrow
•Ag enter – B cell activated
•Ag – tissue – reach – lymph node – spleen
•T cells – activate – B cells
•B cells – Ag binding site – receptors
•Ag – antigenic determinants
•B cells – encounter – Ag - binding

8. Selection of B cells
B cells – surface receptors
Ag – epitopes
Matches
B bind – Ag
Recognition of Ag:
Chemical configuration
Ag determinant – B cell

9. •Processing of Antigen by Macrophages

10. Antigen Presentation
Transfer of Processed
Ag from Macro – B
Thymus dependent
antigens
Can’t activate B cells
TH cells
Macro – interleukin-1
TH – lymphokine
B cell stimulatory
factor (BSF)

11. •Triggering of the B cell
•After – bound with Ag or lymphokine
•Metabolic rate increased
•RNA and protein – synthesis high
•DNA - duplicate

12. Clonal proliferation
Triggered B cell – series of division
5 days
BCGF ( B cell growth factor)
Production of Plasma cells and Memory cells

13. •Secretion of immunoglobulins:
•Synthesised and released in serum
•Circulate – blood
•Specificity – Ag
•Available for secondary IR
•Bind and neutralised - destroyed

14. Factors influencing the Ab formation
Feed back inhibition:
Adjuvants
Route of entry of Antigen
Dose
Nutrition
Genetic factor
Immuno suppressive agents

15. Cell Mediated Immune Response
•Destroy – Ag – cells
•T cells play – major role
•Cellular antigens – handled
•Here cells and tissues – damaged
•Ag remain – cells – ab can’t do any thing
•Cancer – killed – CMI
•Bacteria, virus, fungi, protozoa –targets

16. •T cells
•Macrophages
•Natural Killer cells
•Primary Immune response
•Secondary Immune response

17. Mechanism of CMI ( T cell activation)
•Cellular and protein Ag
•Ag – enter – Tc cells – recognised
•Kill – lysosomal enzymes
•TH cells – lymphokine – macrophage –
accumulate around – Ag – phagocytosis.

18. Recognition of Ag
•Ag enter
•Recongnised – lympho or macro
•T cells – receptors
•Ia antigen (immune associated antigens)
•AGC (antigen presenting cells)
•Ag – have Ag determinant

19. Antigen processing by Macrophages
•T cells – can’t recognise all Ag
•Need – macrophase
•Macro – swallow – Ag – process – it
•Degraded – non immunogenic
components.

20. Antigen presentation by macrophages
•Processed Ag
•Retain – surface
•Ia protein
•Tc or TH

21. Binding of Tc cells with the Antigen

22. Secretion of Tc cell

23. Killing of the Ag by the Tc cell
• Ag – fragmented – lysosomal eyzme
• Apoptotic bodies – apoptosis.

24. Secretion of Lymphokines by TH cells

25. Biological functions of CMI
• Immune surveillance: careful watching,
• Graft rejection
• Delayed type hypersensitivity reaction
• Immunity to viral infection
• Immunity to bacterial infection
• Immunity to parasites