Inhibition of T cell proliferation by the blocking compounds 4, 5, 6, and 7. The T cell clone RN.46 (DR3-restricted) was stimulated with 5 μM KTIAYDEEARR (P261, DR3-restricted peptide; Mycobacterium tuberculosis 65 kDa heat shock protein 3–13) in the presence of increasing concentration of peptide blockers (■) P198, (●) peptide 4, (□) peptide 5, (△) peptide 6, (▽) peptide 7. P198: KPLLIIAEDVEGEY; Mycobacterium bovis 65 kDa heat shock protein 243-255Y. Mean and range is shown.