T dependent and t independent antigens

this slide can help you to know full details about the major type of antigen based on its activity on B or T cell. This slide consists of images to clarify your doubts

1. T dependent and T independent antigens Muthubharathi B C I M.Sc., Biotechnology 2016501012

2. A brief about antigen Ladislas Deutsch, 1899 Induces the production of antibodies Antibody generator Can be recognized by antibody when binds with MHC molecules Soluble compounds

3. Antigen I mmunogenicity Induce the immune response A ntigenicity Binding ability of antigen with antibody or cell surface receptors

4. immunogenicity B cell + Antigen effector T cell + memory B cell T cell + Antigen effector T cell + Memory T cell Plasma cell CTLs, T H cells

5. T dependent antigens Do not directly activates antibodies Depends on T cells for the production of cytokines Cytokines supports the activation, proliferation and differentiation of B cells Cytokines helpful for both cell mediated and humoral immune response

6. T-D antigens elicit memory B cells, which develop in T-D germinal centers Can be identified by somatic mutation in their Ig loci or by surface expression of secondary Ig isotypes

7. T dependent antigens T D antigen B cell antigen receptor peptides MHC II T cell

8. T independent antigens Follicle dendritic cells (FDC) More IgM production Membrane bound immune complex of T-D antigen B cell recptors B cell

9. Easily say that The antigen which directly approaches B cell for antibody production

10. Types T-ID type- I Ag Mitogenic stimuli like LPS, CpG or poly IC and B cell mitogens Function by nonspecifically or polyclonal activity E licit the polyclonal B cell activation via Toll like receptors (recognize microbial molecules, signal cell to secrete immunostimulatory cytokines) T-ID type-II Ag P olysaccharides A ble to activate complements L ack ability to induce MHC dependent T cells Flexible, Hydrophilic, Nondegradable Capable of engaging multiple BCRs

11. Recent study T-ID type II antigens elicit robust and long lasting primary antibody responses in mice but cannot recall response, ie ., secondary immunization Polysaccharide vaccines – P neumovax and Menomune confer long term humoral protection in adult humans T-ID type II stimulate extrafollicular foci of plasma cell production and short lived abortive T-ID germinal centers

12. T-ID type ii antigen Do not induce immunological memory Antibodies to T-ID developed after the age of 2 years Biochemical structure polymeric protein antigen trinitrophenyl-ficoll (TNP) Dinitrophenyl-ficoll (DNP) Eg ., Polysaccharides of bacterial capsule – Streptococcus, H aemophilys , Neisseria

13. B cell or T independent antigen B ound in narrow grooves or deep pockets of the antibody. Protein B-cell epitopes are much larger and interact with a larger, flatter complementary surface on the antibody molecule . But, memory B cells are derived from T-D antigens (Widely accepted)

14. Generation of antibodies to T-Id type ii Membrane immunoglobulin cross linking by multivalent T-ID II ag B lymphocytes activation requires cross linking of a minimum of 10-20 membrane immunoglobulin response Non antigenic specific stimuli Directly target B cell Indirect via injection of Cytokines or expression of co-stimulatory molecules of other cells of immune system or complement compounds

15. T-ID C3b C3b+ T- ID CD21 B cell

16. Role of dendritic cells Dendritic cell T cell activated T cell cytokines B cell B cell Activated B cell Both T dependent and T independent B lymphocyte activation

17. T dependent vs t independent