What accessory molecule aids the T cell receptor in detecting an MHC Class I molecule?

The T cell receptor (TCR) specifically recognizes peptide antigens presented by major histocompatibility complex (MHC) molecules. In the case of MHC Class I molecules, the accessory molecule that assists the T cell receptor in detecting these molecules is CD8. This molecule is found on the surface of cytotoxic T cells, which specifically target and kill infected or abnormal cells.

CD8 acts as a co-receptor that binds to MHC Class I, enhancing the interaction between the T cell receptor and the peptide-MHC complex. This interaction not only stabilizes the binding but also facilitates the activation of the T cell following recognition of the peptide. The presence of CD8 is particularly important in ensuring that the cytotoxic T cells can effectively recognize and respond to cells presenting intracellular antigens.

In contrast, other molecules such as CD3 and CD2 serve different roles within T cell signaling and interaction. CD3 is involved in transmitting signals from the TCR, while CD2 is an adhesion molecule that helps in the formation of the immunological synapse but does not specifically bind MHC Class I. CD4, on the other hand, is associated with MHC Class II molecules and is found on helper T cells. Thus, the role of