RETINOIC ACID-INDUCED MODULATION OF IL-2 MESSENGER-RNA PRODUCTION ANDIL-2 RECEPTOR EXPRESSION ON T-CELLS

Background: Retinoic acid (RA) has important immune-modulating effects on both T and B cell function. Our laboratory has shown that RA can e nhance in vitro polyclonal B cell immunoglobulin (Ig) response. Invest igating cytokines known to affect B cell differentiation, we have rece ntly shown that IL-6 production is augmented by RA. In the present stu dy we have examined the immune modulating effects of RA on IL-2 mRNA, another important cytokine for B cell immunoglobulin production, the e xpression of IL-2 receptors on T cells, and the RA nuclear receptors. Methods: Purified T cells were obtained from adenoidal tissues, and in cubated with RA (10(-7)M) or DMSO solvent/media control for 0, 6-8, an d 24 h. Total mRNA was extracted from T-cells, and using RT-PCR, chang es in the production of IL-2 and RA receptors (RAR)-alpha,beta,gamma m RNA were determined. The effects of RA on IL-2-alpha receptor expressi on was determined by flow cytometry on T cells. Conclusion: These stud ies suggest that RA can augment IL-2 mRNA production by T cells with a possible paracrine effect on IL-2R-alpha expression. These changes ap pear to be mediated by RAR-alpha. Thus, IL-2 may be another important cytokine modulated by RA in the immune response.