Proliferative capacity of chimeric spleen cells, 48 hours after DLI at 3 or 12 weeks.

Two days after DLI at 3 or 12 weeks, spleen cells were stimulated in vitro with mitomycin C–treated host-type splenocytes in a standard MLR. Spleen cells of untreated donor-type mice and of week 3 and week 12 chimeras that had not received DLI were used as controls. Proliferation was determined by (methyl-³H) thymidine incorporation. Results are expressed as SI. Bars represent mean ± SE of 2 (12 weeks) or 4 (3 weeks) identically designed experiments with n = 13 (C3H), 10 (week 3 chim + DLI), 6 (week 12 chim + DLI), 3 (week 3 chim no DLI), and 3 (week 12 chim no DLI). Week 3 and week 12 chimeras not given DLI were unable to generate a proliferative response (SI = 1, SE = 0 and SI = 0.9, SE = 0.07, respectively). *P < .05 for comparison between groups as tested by Kruskal-Wallis multiple comparison Z test. NS indicates not significant.