2. Major Histocompatibility complex OR MHC

3. MHC The principal function of T cells are : The principal function of T cells are : Defense against intracellular microbes Activation of other cells(B cells,Macrophages ) peptide recognition by T and B cells is different. peptide recognition by T and B cells is different. B cells recognize soluble as well as cell associated Ags In contrast,T cells recognize peptide which is displaying only by APC in associated with MHC proteins.

4. MHC MHC genes are the most polymorphic genes MHC genes are the most polymorphic genes MHC genes are codominantly expressed in each individual MHC genes are codominantly expressed in each individual There are two main type of MHC:class I & II There are two main type of MHC:class I & II The physiologic function of MHC molecules is presentation of peptides to T cells,control of immune responsiveness to all proteins and graft rejection The physiologic function of MHC molecules is presentation of peptides to T cells,control of immune responsiveness to all proteins and graft rejection MHC-I present cytosolic peptides to T cytotoxic cells and MHC-II present endocytosed peptides to Th cells MHC-I present cytosolic peptides to T cytotoxic cells and MHC-II present endocytosed peptides to Th cells

5. MHC genes

7. MHC –I structure

8. MHC-II structure

9. T cell receptor and MHC interaction

11. Polymorphism of class II HLA-DPA 12 HLA-DPA 12 HLA-DPB 88 HLA-DPB 88 HLA-DQA 17 HLA-DQA 17 HLA-DQB 42 HLA-DQB 42 HLA-DR >400 HLA-DR >400

12. Polymorphism of class I HLA-A >280 HLA-A >280 HLA-B >500 HLA-B >500 HLA-C >130 HLA-C >130

13. MHC genes and graft rejection

14. HLA expression

15. Peptide presentation by MHC-II

16. Peptide presentation by MHC-I