THE RECOGNITION OF THE NONCLASSICAL MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) CLASS-I MOLECULE, T10, BY THE GAMMA-DELTA T-CELL, G8

Recent studies have shown that many nonclassical major histocompatibil ity complex (MHC) (class Ib) molecules have distinct antigen-binding c apabilities, including the binding of nonpeptide moieties and the bind ing of peptides that are different from those bound to classical MHC m olecules. Here, we show that one of the H-2T region-encoded molecules, T10, when produced in Escherichia coli, can be folded in vitro with b eta(2)-microglobulin (beta(2)m) to form a stable heterodimer in the ab sence of peptide or nonpeptide moieties. This heterodimer can be recog nized by specific antibodies and is stimulatory to the gamma delta T c ell clone, G8. Circular dichroism analysis indicates that T10/beta(2)m has structural features distinct from those of classical MHC class I molecules. These results suggest a new way for MHC-like molecules to a dopt a peptide-free structure and to function in the immune system.