THE FUNCTIONAL HALF-LIFE OF H-2K(D)-RESTRICTED T-CELL EPITOPES ON LIVING CELLS

The functional half-life (t(1/2)) of different complexes formed by maj or histocompatibility complex (MHC) class I molecules and antigen on t he surface of target cells was measured using specific cytotoxic T lym phocyte (CTL) clones in cytolysis, and interferon-gamma-production and Ca2+-mobilization assays. Functional t(1/2) values of 5-10 h were obt ained, which are in accordance with some previous estimations obtained from biochemical and immunochemical measurements. Moreover these valu es were independent of the type of target cell, fixation of the target cells, or proteases able to degrade the peptides, suggesting that the unfolding of the peptide/MHC complexes at the cell surface alone dete rmines the functional t(1/2) of the CTL epitopes.