MHC

MHC

1. Innate VS Adaptive

2. Self Discrimination

   • Definition : distinguish nonself from self, a delicate balance between tolerance to self and response/rejection of nonself . When there is an imbalance, autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus (SLE), myasthenia gravis and multiple sclerosis occurs.
   • The body is able to identify itself from foreign objects because a persons genes are codominant meaning that it is the combination and variation of two other genes (parents) making a unique set of genetic codes.
   • Each person contains a unique HLA (Human leukocyte antigen), which is responsible for rejecting the transplant
     • HLA is made up of a group of loci in a tandem array along the chromosome 6 split into MHC 1 and MHC2

3. Cellular Responce (MHC 1)

   • it is the bodies identity card expressed on the surface of every cell
   • TCR on CD8+ cytotoxic T cells responds and recognises Ag only when bound to MHC class I molecule context (MHC I restriction).

4. Humoral Responce (MHC 2)

   • Only expressed on the surface of APC cells (immune responce)
   • TCR on CD4+ helper T cell recognises and responds to Ag only when bound to an MHC class II molecule context (MHC II restriction

5. MHC molecules “select” the antigen epitope to be recognised by T-cell receptor

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