Sixty-day survival of B10.BR mice transplanted with allogeneic C57.BL6 BM and splenocytes. Recipient mice received 10 Gy irradiation in 2 equal fractions on day −2 or day −1 and transplanted with 0.5 × 10⁶ BM cells from C57.BL6 donors on day 0. The 60-day survival of groups of 7 to 21 mice in 14 separate experiments receiving various numbers of irradiated (7.5 Gy) (▴) or nonirradiated (○) allogeneic splenocytes given in 1 to 3 injections on consecutive days around the day of BM transplant (day 0). Best-fit lines are shown for the survival of mice receiving different doses of irradiated allogeneic splenocytes (—) (r² = .49) and unirradiated allogeneic lymphocytes (— — —).