Fig. 2.
The persistence of peptide:class II ligand controls the ability of CD4 T cells to expand during responses to unrelated peptide antigens. (A) Mice were immunized with the low-stability peptides OVA[327-339], OVA V1, OVA V2, LACK V1, HEL[11-25], MalE V1 (white bars) or high-stability peptides OVA V3, LACK[156-173], HEL V1, MalE[69-84], and MalE[102-115] (black bars) to assess the ability of these peptides to elicit T cell responses when immunized with a mixture of dominant peptides. The results are presented as the percentage of the response gained or lost with competitor peptides in the immunization, relative to the peptide alone responses and are an average, from triplicate wells of IL-2 ELISpots of the indicated number of experiments ± SEM. Shown beneath each bar is the number of experiments performed. (B) Percentage loss or gain of T cell activation of the indicated peptides was quantified across experiments by comparing the total number of antigen-specific IL-2 responders from test peptide immunized alone to test peptide immunized with competitors at the peak of the immune response. The percentage of the response with competitors was then plotted against the t1/2 in association with I-Ad of the peptide:class II complex under study. The data points were subjected to Spearman's nonparametric test, resulting in an r2 value = 0.7818, P < 0.0064 (significant correlation).