The HLA class III region genes are impoant elements in -
Responses of MHC molecules Class I MHC class I molecules bind and process peptide that are derived from proteins synthesized within the cells, e.g. viral protein in viral infected cells and antigen of cancerous cells. These cells (cancerous or virus infected) have a tendency to display unusual, non self antigens on their surface After binding to MHC-I, these antigens are processed and presented to cytotoxic CD-8 T cells (MHC-I restricted). Cytotoxic CD-8 T cell - MHC I reaction cause - Graft rejection Cell mediated cytolysis of viral infected or tumor cells. Class II Class II molecules present exogenous antigen (e.g. extracellular microbes, soluble proteins). These antigens are first internalized and undergo proteolytic cleavage in lysosome. Peptide generated from this proteolytic cleavage are presented by MHC - II to CD4-T cells (MHC-II restricted) Reactions are Graft versus host response Mixed leukocyte reaction Class III "The MHC class III region contains many genes that are good candidates for the involvement in autoimmune disease". Recent data suggest that quantitative and qualitative diversities of the MHC III linked C4 among different ethnic groups can be impoant in susceptibility to autoimmune disease like SLE. Also Know The pa of MHC complex that code for TNF alpha & Beta and heat shock protein, is also referred as class IV MHC. -
Transplant rejection phenomenon
Governing susceptibility to autoimmune disease
Immune surveillance
Antigen presentation and elimination