Figure 2.
Blockade of CTLA-4 during priming results in an increase in responders to the priming peptide. CTLA-4 blockade results in increased IFN-γ- (A) and IL-4- (B) secreting responders to PLP-139–151 in animals immunized with PLP-139–151. Anti-CTLA-4 results in increased IFN-γ- (C) but not IL-4- (D) secreting responders (D) to PLP-Q in PLP-Q-immunized animals. Animals (four or five per group) were immunized with PLP-139–151 or PLP-Q and control (solid lines) or anti-CTLA-4 antibody (dashed lines) as described in Materials and Methods. ELISPOT analysis was performed on day 8. Draining lymph nodes were pooled and cells were stimulated at 5 × 105 cells per well in wells coated with capture antibody for IFN-γ or IL-4, with the indicated concentrations of peptide for 36 h. A and B are representative of four experiments whereas C and D represent two of three experiments (IL-4 responders increased in one experiment). Data points represent the means of triplicate wells. Error bars represent standard deviation. For IL-4, the number of peptide-specific responders represents the numbers of spots in the presence of peptide minus the number of IL-4 secretors in the control wells without peptide.