Effect of minimal irradiation on engraftment. Balb/c female hosts received graded doses of whole animal irradiation (0, 10, 20, 50, and 100 cGy) followed 4 hours later by infusion of 40 × 106 normal Balb/c male marrow cells of the same strain in a single injection. To evaluate repopulation patterns by Southern blot analysis, we used the Y-chromosome specific pY-2 probe. Female recipient mice were killed 2 months after 0, 10, 20, 50, and 100 cGy and infusion of male marrow cells with 5 to 10 transplanted animals per dose level. A dose of 100 compared with 0 cGy showed increased engraftment in marrow, spleen, and thymus (P < .01). At 20 and 50 cGy, both bone marrow and spleen engraftment was increased compared with 0 cGy (P < .02). Compared with 50 cGy, 100 cGy produced superior engraftment in spleen, thymus, and marrow (P< .01).
