Figure 3.

Pre-existing anti-CM immunity enhances anti-donor T cell responses despite DST/MR1. A. Top: Spleen cells were obtained 2 weeks after B6 heart transplantation and DST/MR1 treatment in groups of animals pre-immunized with CM/CFA, CFA alone or not pre-immunized, and tested for frequency of donor (B6) reactive IFNγ producers by ELISPOT. *p<0.05 vs. none and CFA alone. Bottom: In a separate set of control experiments spleen cells were obtained from a) BALB/c mice 2 weeks after B6 heart transplantation and DST/MR1 treatment that were pre-immunized with CM/CFA, b) untreated BALB/c recipients of B6 hearts at rejection (day 8 posttransplant) and c) naïve BALB/c mice. The spleen cells were tested in IFNγ ELISPOT assays for reactivity to B6 and third party (3P) C3H spleen cells (*p<0.05). B. Top: Sera were obtained 2 weeks after transplant from DST/MR1 treated B6 allograft recipients that were either unimmunized mice (none), pre-immunized with CM/CFA, or pre-immunized with CFA alone, and tested by flow cytometry for binding to B6 thymocytes. Bottom: In control experiments, sera were obtained from naïve mice and from untreated mice 3 months after rejecting a B6 allograft, and tested by flow cytometry for binding to B6 thymocytes. None of the sera bound to syngeneic BALB/c thymocytes (not shown). *p<0.05 versus other groups. *p<0.05 versus other groups on the same graph.