CD4⁺ T cells in ECP-treated mice show reduced expression of homing and activation markers. Donor CD4⁺ T cells (H2^b) were reisolated at day +4 post-BMT and fold change based on Tcon as reference group is shown. Expression of activation markers CD69 and CD44 in spleen and pLN and gut homing marker α4β7 in mLN are significantly reduced, with skin homing marker p-selectin in pLN showing a similar trend. Data are pooled from 2 independent experiments with 7 mice per group. Error bars indicate mean ± SEM and significance was assessed by 2-tailed Student t test.