TGFB1 and systemic lupus erythematosus: In this context, interleukin‐2 (IL‐2) and transforming growth factor β (TGF-β) are deficient in SLE, and these cytokines play critical roles in immunoregulatory responses such as the induction and maintenance of CD4+ and CD8+ T regulatory cells (Tregs) (2–5).