Donor T-cell cytokine and cytolytic functions after BMT.

B6 Ly5.2 (CD45.1⁺) animals were irradiated and received BM transplants from BALB/c donor mice that had been injected with control diluent (▪) or IL-18 (░) as in Figure 1. Splenocytes from the recipients (n = 3/group) were harvested and combined on day 7 after BMT. Splenocytes were normalized for donor T cells (CD45.1^-and CD3⁺) and restimulated in quadruplicate with irradiated naive host (B6 Ly5.2) splenocytes in MLR cultures. Supernatants were collected after 48 hours of culture for cytokine measurement. Proliferation was determined by incubation of cells with³H-thymidine (1 μCi/well [0.037 MBq]) for an additional 24 hours. T cells from IL-18–treated donors produced significantly (A) less IFN-γ (▪ vs ░; *P < .05), (B) more IL-4 (▪ vs ░; **P < .01), and (C) less proliferation (▪ vs ░; *P < .05) in MLR cultures. (D) IL-18 treatment preserves CTL function after BMT. Splenocytes harvested from allogeneic animals on day 14 after BMT were pooled (n = 3/group), and normalized for donor CD8⁺ cells and used in a ⁵¹Cr release assay. CTL activity against allogeneic targets (EL4) in control (▴) and IL-18 (●) groups was similar, while there was no significant lysis of syngeneic targets (P815) by both the groups (○ and ▵). Error bars represent standard error.