Epitopes of the class I major histocompatibility complex (MHC‐I) recognized in the syngeneic or allogeneic context predominantly linked to antigenic peptide loading to its binding groove
Class1 major histocompatibility complex (MHC‐I)–antigenic peptide exposed at the target cell surface is crucial for the adaptive immune response exerted in the self/syngeneic context by cytotoxic T lymphocyte (CTL). Such a complex also provides epitopes in the allogeneic context for antibody response directed against the MHC‐I polymorphic determinant. In the present report we examined the formation of the MHC‐I–peptide complex leading predominantly to the expression of T and/or B cell epitopes in a process of internal versus external antigenic peptide loading onto the binding groove of MHC‐I. Analyses using antibodies specific to complex MHC‐I–peptide generated in the syngeneic context to mimic T cell receptor (TCR) in comparison with antibodies specific to the MHC‐I polymorphic determinant allowed the observation that the external peptide loading to MHC‐I, while remaining necessary for inducing the formation of B cell epitopes, was less efficient than the internal one for generating T cell epitopes. Thus, external loading of peptide to the MHC‐I appeared to match more closely the allogeneic situation and the humoral immunity in general, while internal peptide loading corresponded with the self/syngeneic context of the cellular CTL response.