Inhibition of PARP-1 in human CD4⁺CD25^–T cells increases the expression of FOXP3 and TGFBR1. CD4⁺CD25^– T cells were isolated from human peripheral blood and preincubated with 5-AIQ for 20 minutes, then cells were stimulated with human CD3- and CD28-specific antibodies for the indicated time. Quantitative PCR analysis showed the expression of FOXP3, TGFBR1, and TGFBR2. (A) FOXP3 expression was determined after 12 hours of culture. Data are mean ± SEM of 3 independent experiments. (B) TGFBR1 and TGFBR2 mRNA expression was determined after 90 minutes of culture. Data are mean ± SEM of 3 independent experiments. *P < .05 (unpaired 2-tailed Student t test).