IMMUNOLOGY

Detailed explanation-1: -Answer. Answer: Antigen recognition by alloreactive MHC class I-restricted CD4(+) T cells was inhibited by removing peptides bound to HLA molecules on T2 cells suggesting that the alloreactive CD4(+) T cells recognize peptides that bind in a TAP-independent manner to HLA-A2 molecules.

Detailed explanation-2: -In both complexes, CD4 binds MHC class II through its membrane-distal D1 domain, which contacts the membrane-proximal 2 and 2 domains of the MHC class II molecule (Figure 2A).

Detailed explanation-3: -Because the binding of the coreceptors to MHC molecules stabilizes weak interactions between TCRs and peptide–MHC (pMHC) complexes, CD8+ T cells are MHC class I-restricted whereas CD4+ T cells are MHC class II-restricted.