Abstract： Retinoic acids have been increasingly applied in the clinic practice of dermatology.Recent studies have shown that retinoic acids can modulate immune cells(namely,inhibiting the activity of NK cells)and enhance the ability of antigen presenting cells.At the same time,they can influence the proliferation and apoptosis of T cells via binding different receptors,inducing production of regulatory T cells.Moreover,they can induce the shift of specific immune response to humoral immunity by reinforcing the differentiation of T helper cells,affecting the proliferation of B cells and increasing the secretion of antibodies by plasmocytes.The immunomodulatory effect may be affected by the dose of retinoic acids.