Comparison between NZB T-cell proliferative response to peptide 861-874 and 861-875 (Glu861, Lys875). A splenic T-cell pool from DAT-positive NZB mice was cultured with varying concentrations of peptide 861-874 or 861-875 (Glu861, Lys875). The data are the mean values of the peak responses on day 6. In the absence of antigen, the proliferative response was less than 1200 cpm.