Polyclonal Recipient nTregs Are Superior to Donor or Third-Party Tregs in the Induction of Transplantation Tolerance

Figure 6

Chimeras induced through recipient Treg treatment demonstrate donor-specific hyporesponsiveness in vitro and humoral tolerance. (a) Mixed lymphocyte reaction results from selected BMT recipients were obtained 28–37 weeks after BMT. Chimeras of recipient Treg treated mice () showed specific hyporesponsiveness to donor antigens in vitro ( SI anti-donor compared to third-party antigen; SI anti-donor compared to naïve B6 mice, ). Donor reactivity was preserved in BMT recipients that were treated with donor () or third-party () type Tregs. SIs were calculated by dividing the mean cpm from responses against recipient (black column; B6), donor (white column; Balb/c), or third-party (grey column; C3H) stimulator cells by mean background cpm (i.e., cpm with no stimulator population). Error bars indicate standard deviation. (b) BMT recipients were analyzed for the existence of anti-donor antibodies in serum >3 months after BMT (i.e. ~1-2 months after skin grafting). Recipient Treg induced chimeras () uniformly failed to develop detectable levels of anti-donor antibodies, whereas BMT recipients treated with donor () or third-party () Tregs and control mice without Treg treatment (but receiving BM, costimulation blockade, and rapamycin; ) developed substantial antibody levels. The reactivity of sera with syngeneic (B6; grey filled area) and donor (Balb/c; black line) thymocytes is shown by flow cytometry through indirect staining with anti-mouse IgG. Representative histograms are shown.

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