FIGURE 7.

Higher affinity MHC-TCR interactions produce an additive activation signal over time. A, Purified P14 CD8⁺ cells were stimulated with D^b/gp33 or D^b D227K/gp33 tetramers and activation of p56^Lck kinase was measured. D^b D227K/gp33 stimulated significantly higher kinase activity than irrelevant or no tetramer (**, p < 0.005). However, D^b/gp33 induces significantly greater p56^Lck activity than D^b D227K/gp33 (*, p < 0.005). Data are representative of three independent experiments. B, Purified P14 CD8⁺ cells were stimulated with D^b/C9M or D^b D227K/C9M tetramers for 15 min or 2 h and washed away. Control cells received tetramer stimulation for the entire course of the assay (36 h). Data are representative of two independent experiments.