Lyt-phenotype conversion of cytotoxic T lymphocytes specific for the A and E class II major histocompatibility...

The Lyt-1+ (high) Lyt-2+/- (low) primary cytotoxic T lymphocytes (CTL) specific for A(A alpha A beta) molecules and the Lyt-1+Lyt-2+ primary E(E alpha E beta)-specific CTL are both shown to become Lyt-1 Lyt-2+ effector cells after secondary in vitro stimulation. Thus CTL specific for class II major histocompatibility complex molecules exhibit the same Lyt-phenotype shift as class-I-specific CTL do. The data suggest that either both class-I-specific and class-II-specific CTL follow the same differentiation pathway or regulatory cellular interactions allow only Lyt-1-Lyt-2+ cells to differentiate to secondary CTL.