Dk-restricted antiinfluenza cytotoxic t-cell clone loses one of its two alloreactivities

K6, an influenza-specific cytotoxic T (Tc)-cell clone derived from C3H/He mice, was D^k-restricted. Further analysis showed that K6 also recognized D^d and D^q as allotargets. The clonal nature of the three recognition specificities was confirmed by cold-target cell inhibition. After extensive in vitro selection, K6 lost the ability to lyse D^d cells while retaining both other specificities. The role of the Lyt-2 molecule in antigen-specific self-H-2-restricted vs allospecific recognition was investigated by inhibition with the Lyt-2-specific monoclonal antibody 53-6.7. Both activities were proportionately inhibited, indicating that the Lyt-2 molecule is equally important for both recognition specificities of this Tc-cell clone.