Major histocompatibility complex class I molecule selves as a ligand for presentation of the superantigen staphylococcal enterotoxin B to T cells

Superantigens, such as staphylococcal enterotoxin B (SEE), elicit a strong proliferative response in T cells when presented in the context of major histocompatibility complex (MHC) class II molecules. We observed a similar T-cell response, when MHC class II-negative epidermal cell lines were employed as antigen-presenting cells, Immunoprecipitation studies indicated that the ligand to which SEE bound had a molecular mass of 46 kDa, Radiolabeled SEE could be immunoprecipitated from isolated membrane proteins on the SCC13 epidermal cell line with a monoclonal antibody directed against the MHC class I molecule, and transfection of the K-562 cell line with MHC class I molecules showed a 75% increased SEE-binding capacity compared with the nontransfected MHC class I- and class II-negative counterpart, In functional studies, antibodies to the MHC class I molecule inhibited T-cell proliferation by at least 50%, From these studies, we conclude that MHC class I molecules on malignant squamous cell carcinomas serve as ligands for SEE, which, given the appropriate costimulatory signals, is sufficient to allow for superantigen-induced T-cell proliferation.