Question

Compare the functions of proteins in the B7 and CD28 families.

Answer 1

* B7

- is a peripheral membrane protein found on activated antigen presenting cells

- when paired with either a CD28 or CD 152 surface protein on T cell can produce a costimulatory signal or a coinhibitory signal to enhance or decrease the activity of MHC - TCR signal between the antigen presenting cells and T cells .

- Binding of the B7 of antigen presenting cell to CTLA - 4 of T cells causes inhibition of the acrivity of the T cells.

* CD28

- it is one of the protein expressed on T cells that provide co stimulatory signals required for activation and survival of T cells.

- it plays a centsl role in immune response against pathogens , autoimmune disease and graft rejection .