The document summarizes the immune response, including both humoral and cell-mediated responses. The humoral response involves the production of antibodies by B cells to destroy pathogens outside cells. The cell-mediated response involves T cells and macrophages that destroy pathogens and infected cells. The response begins with antigen presentation to B cells or T cells, followed by cell activation, proliferation, and the production of antibodies or lymphokines to eliminate the antigen. Both primary and secondary immune responses are discussed.

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