Fig. 2. Conditioning regimens with Bcl-2i deplete conventional T cells, B cells, and NK cells without affecting T_reg cells.

(A) Our original conditioning regimen (group A) included 3-Gy TBI in addition to thymic irradiation, ATG, CB (costimulatory blockade; with anti-CD154 mAb), and a 28-day course of CyA. In groups B and C, TBI was reduced to half (1.5 Gy) without or with Bcl-2i, respectively. In group D, TBI was removed from the regimen. (B) BAX expression on T cells isolated from groups B and C was measured by flow cytometry in the peritransplant period. Expression is shown relative to baseline (pretreatment). T_naïve, naïve T cells, CD3⁺CD95⁻CD45RA⁺; T_EM, effector memory T cells, CD3⁺CD95⁺CD28⁻; T_CM, central memory T cells, CD3⁺CD95⁺CD28⁺. MFI, mean fluorescence intensity. (C) Absolute counts of various peripheral lymphocytes in group B (blue dotted lines) and group C (magenta lines) are shown, including naïve T cells, T_EM, T_CM, B cells (CD3⁻CD20⁺), and NK cells (CD3⁻CD16⁺NKG2a⁺) (n = 4, group B; n = 5, group C; each sample was obtained from different NHPs). (D) Representative flow cytometry dot plots show Bcl-2 expression on Foxp3⁻ and Foxp3⁺ cells among CD3⁺CD4⁺ T cells (left panels). Bcl-2 expression was measured longitudinally in T_reg cells and non-T_reg CD4⁺ T cells (right panel) (n = 4, each sample was obtained from different NHPs). (E) The frequency of T_reg cells among CD4⁺ T cells was measured in group C (magenta line) and group B (blue dotted line) recipients (%) (n = 5, group B; n = 6, group C; each sample was obtained from different NHPs). Data are presented as means ± SE. Data were analyzed using mixed-model ANOVA for repeated measure. NS, not significant. Tx, transplantation.