DIMERIZATION OF SOLUBLE MAJOR HISTOCOMPATIBILITY COMPLEX PEPTIDE COMPLEXES IS SUFFICIENT FOR ACTIVATION OF T-CELL HYBRIDOMA AND INDUCTION OF UNRESPONSIVENESS

Major histocompatibility complex (MHC) class I molecules are cell-surf ace proteins that present peptides to CD8(+) T cells. These peptides a re mostly derived from endogenously synthesized protein. Recombinant, soluble MHC class I molecules were produced, purified, and loaded homo geneously with synthetic peptide. These MHC-peptide complexes were use d to activate a T cell hybridoma. While monomers of MHC-peptide bound to the T cell, they showed no stimulatory activity. Dimers fully trigg ered the T cell hybridoma to secrete interleukin 2. This response was followed by a state in which the T cell was refractory to restimulatio n as a result of defective signal transduction through the T cell rece ptor.