Retinoic acid suppression of human leukocyte interferon production

Retinoic acid (RA) suppressed the production of interferon (IFN) alpha and IFN gamma of human peripheral blood leukocytes in response to stimulation with lectin mitogens, bacterial products, synthetic polynucleotides, viruses, and tumor cell lines in vitro. Virus-induced secretion of IFN alpha of human lymphoblastoid cells was also inhibited. RA-mediated suppression was dose-dependent and required the near-concurrent addition of RA and inducers to human leukocyte cultures, thus suggesting that RA affects an early cellular function in the generation of IFN. Implications of these findings for the use of retinoids in the treatment of human malignancies are discussed.