Lecture-3 Evaluation of the role of T-cells in adaptive immune response.

The participation of immunoglobulins, the tailored products of B-cell, as humoral components in adaptive immune response will be appreciated.
The principle behind the concept of vaccine and its function will be interpreted.

1. Lecture-3 ADAPTIVE IMMUNITY Prof. Sreerama Krupanidhi Email: [email protected]

2. Objectives To define adaptive immunity. To acquaint with the components of adaptive immunity. To evaluate the role of T-cells in adaptive immune response. To evaluate the role of B-cells in adaptive immune response. 8/29/2024 2 Prof. Sreerama Krupanidhi

3. Expected Outcomes Role of adaptive immune response in the protection of host system will be understood. The participation of T-cells and B-cells as cellular components in adaptive immune response will be known. The participation of immunoglobulins, the tailored products of B-cell, as humoral components in adaptive immune response will be appreciated. The principle behind the concept of vaccine and its function will be interpreted. 8/29/2024 Prof. Sreerama Krupanidhi 3

4. Adaptive Immunity Immunity acquired by infection or vaccination (active immunity) or by the transfer of an antibody or lymphocytes from an immune donor. Adaptive immunity is defined by the presence of lymphocytes namely T and B cells that receive antigen and produce antibodies & memory B-cells. 8/29/2024 4 Prof. Sreerama Krupanidhi

5. Nature of antigens Anti body gen erator Includes an enormous variety of materials Antigen is a compound that elicits an immune response Antigen that causes immune response by mediating T- cells is termed as an immunogen Proteins and polysaccharides induce string response Lipids and nucleic acids often do not. Recognition of an antigen is directed at antigenic determinant site or epitope. 8/29/2024 5 Prof. Sreerama Krupanidhi

6. Strategy of AI Response Immune system remembers pathogen. First response to antigen is called primary response. May take a week or more to develop. In subsequent exposure Termed secondary response Adaptive immunity divided into Humoral immunity Humoral components Eliminate extracellular pathogens Cellular immunity Competent cells Eliminate intracellular and extra cellular pathogens. Primed B- cells transform as Memory cells 8/29/2024 6 Prof. Sreerama Krupanidhi

7. B-Lymphocyte: Antibody Response Characteristic of primary response Lag period of 10 to 12 days occurs before antibody detection in blood after vaccination Activated B cells proliferate and differentiate into increasing numbers of plasma cells as long as antigen is present 8/29/2024 7 Prof. Sreerama Krupanidhi

8. B-Lymphocyte: Antibody Response Net result is slow steady increase in antibody titer 8/29/2024 8 Prof. Sreerama Krupanidhi

9. T-Lymphocyte: Ag Recognition and Response General characteristics of T cells Have multiple copies of T cell receptors: Receptors have variable sites for antigen binding. Role of T cells are different from B cells: T cells never produce antibodies T cells armed with effectors that interact directly with antigen T cell receptor does not react with free antigen Antigen is presented by APC to T cell 8/29/2024 9 Prof. Sreerama Krupanidhi

10. T Lymphocytes Antigen Recognition and Response General Characteristics During antigen presentation, antigen cradled in the grove of major histocompatibility complex molecule (MHC molecule) Two types MHC MHC class I Bind endogenous antigen and viral antigens MHC class II Bind exogenous antigen 8/29/2024 10 Prof. Sreerama Krupanidhi

11. T Lymphocytes: Antigen Recognition and Response Role of T H cells in macrophage activation 8/29/2024 11 Macrophages routinely engulf invading microbes resistant to lysosomal killing. Prof. Sreerama Krupanidhi

12. T Lymphocytes Antigen Recognition and Response Role of T H cells in macrophage activation 8/29/2024 12 Phagocytosed microbe gets hydrolysed into fragments and peptides in the Phagosome of Macrophage. Prof. Sreerama Krupanidhi

13. T Lymphocytes Antigen Recognition and Response Role of T H cells in macrophage activation 8/29/2024 13 Peptide fragment presentation through MHC Class II. Prof. Sreerama Krupanidhi

14. T Lymphocytes Antigen Recognition and Response Role of T H cells in macrophage activation 8/29/2024 14 T H Cell T H cell recognizes the antigenic signal as the same is presented by MHC II. Prof. Sreerama Krupanidhi

15. T Lymphocytes Antigen Recognition and Response Role of T H cells in B cell activation If T H cell bearing peptide + MHC class II complex encounters B cell T H cell responds by producing cytokines B cell is activated in response to cytokine stimulation B cell proliferates and undergoes class switching Also, drives formation of B memory cells 8/29/2024 15 Prof. Sreerama Krupanidhi

16. Lymphocyte Development During lymphocyte development, B and T cells acquire ability to recognize distinct epitopes Once committed to specific antigen, cells ensure proper (tailored) function B cells undergo developmental stages in bone marrow T cells go through developmental process in thymus 8/29/2024 16 Prof. Sreerama Krupanidhi

17. SUMMARY OF ADAPTIVE IMMUNE RESPONSE 8/29/2024 17 Prof. Sreerama Krupanidhi

18. Summary of AIR 8/29/2024 18 Prof. Sreerama Krupanidhi

19. Summary of AIR 8/29/2024 19 Prof. Sreerama Krupanidhi

20. Summary Antibody generator is an antigen. AI means adaptive (acquiring) immunity (developing immune memory) against a pathogen to which we expose. Two types of AI : Humoral and cellular. Humoral immunity is through Igs which neutralizes specifically with epitopes of antigen. B-cells produce Igs . Cellular immunity is regulated by T-cells. Activated T and B cells undergo clonal selection. Role of T H cells in B-cell activation and Macrophage activation is known. 8/29/2024 20 Prof. Sreerama Krupanidhi

21. Study Questions Define Adaptive Immunity. How does the concept of AI help us to understand the vaccine development? . How do T helper cell activate macrophage? How do T helper cell regulate to activate B-Cell? Display a labeled diagram showing adaptive immune responses. When do macrophage/DC interact with Th cell? How do Th cell get primed? 8/29/2024 21 Prof. Sreerama Krupanidhi

22. Acknowledgements 8/29/2024 22 We acknowledge the online resources and public domains for the Preparation of the content to develop teaching material and for the dissemination of knowledge. Prof. Sreerama Krupanidhi

23. Thank you 8/29/2024 Prof. Sreerama Krupanidhi 23