TSLP interacts with thymocytes to affect FoxP3 expression and Treg maturation. Thymocytes from day 2 newborn mice were cultured with or without TSLP in mFTOC medium for 2 days. Cells were harvested and analyzed by FACS and real-time PCR. A and B: TSLP increased maturation of SP, CD4+CD25+ thymocytes and FoxP3 expression. Shown are data repeated in at least three independent experiments. C: Absolute numbers of CD4+CD8-, CD4+CD8-CD25+ and FoxP3+CD4+CD8-CD25+ in cultures started with initial 10 × 106 total thymocytes from day 2 neonatal mice. Data show mean and standard deviation from three different experiments. * indicates p < 0.05 by student's t test. D: TSLP induced FoxP3 expression in thymocytes from day 2 neonatal mice. Thymocytes were cultured with or without TSLP for 2 days and analyzed by real-time PCR as above. * indicates p < 0.05.