What are the similarities between C4 cells and CD8 cells?

CD4 and CD8 are both types of surface proteins that are generated in the thymus and found on the extracellular surface of their respective cells. Both belong to the immunoglobulin superfamily and are considered as glycoproteins. Both CD4 and CD8 cells express the T-cell receptor. In the absence of T-cell receptors, both can bind to MHC molecules. Both can also enhance the production of the antigen-induced IL-2 via different mechanisms.