To assess the effect of PLGA‐ATRA MP on Treg stability, CD4+tdTom+ T cells after arthritis induction were compared between littermates that received IA PLGA‐ATRA MP or PLGA‐Blank MP, analyzing the pooled draining lymph nodes (inguinal and popliteal), pooled ankles, and the spleen. Here, CD4 is linked to Arthritis.