Short-term engraftment of male BM and transient expansion of DBY-Tregs. (A-B) Short-term engraftment (day 28) of congenic male 45.1 BM (5 × 10⁶ cells) transferred into B6 female 45.2 mice either untreated (-) or conditioned with one intravenous injection of a various number of DBY-Tregs or 1 × 10⁶ B6-Tregs. Male B6 mice were engrafted as a positive control (CTRL). Percentages of CD45.1⁺ donor cells were analyzed in PBMCs. Results represent the mean of 3 to 6 mice per group ± standard error of the mean (SEM). (C) Transient expansion of DBY-Tregs. DBY-Tregs (1 × 10⁵ cells) were transferred into B6 female mice with or without male BM (10⁷ cells). At each time point, mice were killed and their splenocytes stained with CD45.1 and CD4. Graph represents the percentage of CD45.1⁺ cells in CD4⁺ 7-AAD^– cells. Results represent the mean of 2 mice killed at each time point from groups of 8 mice per condition. Bars represent the 2 values of single-animal results.