Absence of host γδ T cells reduces allogeneic donor T-cell responses. (A,B) γδ^-/- (▥, n = 4), wt (▪, n = 4), and syn BM transplant recipients (□, n = 4) underwent transplantation as in Figure 1. Splenocytes were harvested on day 7 after BMT, and donor (H2D^d+) CD4⁺ T-cell (A) and CD8⁺ T-cell (B) phenotype were determined by FACS analysis as described in “Materials and methods.” Data represent the mean ± SE. wt vs γδ^-/-, ^*P < .05. (C-E) Splenic DCs were isolated from γδ^-/- (▴) and wt (•) mice 6 hours after 1100 cGy TBI and were cultured for 3 to 4 days with allogeneic responder BALB/c T cells. During the final 12 hours of a 96-hour culture, cells were pulsed with [³H] thymidine and assayed for proliferation (C). Supernatants were collected at 48 hours and 72 hours and assayed by ELISA for IL-2 (D) and IFN-γ (E), respectively, as described in “Materials and methods.” Each graph represents 1 of 4 similar experiments. wt vs γδ^-/-, ^*P < .05. Error bars represent standard error.