OX40L expression on donor T cells and regulation of GVHD lethality.

OX40L expression on donor T cells is not a potent regulator of CD4⁺ T-cell–mediated GVHD lethality. (A) Sublethally irradiated bm12 recipients (n = 8 per group per experiment) were given highly purified CD4⁺ T cells (10⁵) from either 129/Sv OX40L^−/− (○) mice or OX40L^+/+(●) littermate controls, as indicated. Data from 2 replicate experiments with similar results are pooled. Groupwise comparisons revealed that P = .24. (B) Sublethally irradiated bm1 recipients (n = 5 per group) were given highly purified CD8⁺ T cells (1 or 3 × 10⁶, as indicated in parentheses) from either 129/Sv OX40L^−/− mice or OX40L^+/+ littermate controls. No signficant differences were noted between relevant groups. (C) Antiasialo-GM1 antisera–pretreated BALB/c–SCID mice were given purified CD4⁺ T cells (10⁶) from 129/Sv OX40L^−/− (▵) mice or OX40L^+/+ (▴) littermate controls (n = 5 per group). Survival was not improved in recipients receiving OX40L^−/− versus OX40L^+/+CD4⁺ T cells.