Comparison of IS formation and signaling for a panel of seven self-reactive and two antiviral T cell clones. Parameters characterizing IS formation and signaling were compared using a color-coded grading system. Red indicates a response between 80 and 100% of the maximum response; orange, 50 and 80%; yellow, 20 and 50%; and light yellow, 0 and 10%. For motility, red represents <0.1 µm/min; orange, <0.2 µm/min; yellow, <0.5 µm/min; and light yellow, >0.5 µm/min. For proliferation, red corresponds to an EC₅₀ <0.005 nM peptide; orange, <0.5 nM; yellow, <5 nM; and light yellow, >50 nM.