RESUMEN
Objective :To study the effect and mechanism of retinoic acid(RA) on thymocytes development. Methods:Thymus tissue culture system was used to investigate the roles of RA in maturation development of thymocytes. Thymus tissues were cultured with or without retinoic acid and/or retinoic acid receptor antagonist. The cultures were harvested after 24, 48 and 72 hours, respectively. Thymocytes were stained with fluorescence labeled anti-CD3, anti-CD4, anti-CD8 antibodies and analyzed by flow cytometry. The real time quantitative RT-PCR assay was used to detect the retinoic acid receptor (RAR) mRNA expression in thymocytes. Results:The thymus tissue culture system was able to support the maturation of thymocytes. Addition of RA to the culture system promoted thymocytes differentiation from immature CD4+CD8+ cells to mature CD4+ cells, but inhibited the transformation from immature CD4+CD8+ cells to mature CD8+ cells. The effect was marked after 24h culture, and was antagonized by Ro41-5253. RA enhanced the expression of RAR mRNA in thymocytes. A positive correlation was found between the expression of RAR mRNA and the percentage of CD4+CD8+ cells and a negative correlation between the expression of RAR mRNA and the percentage of CD8+ cells. Conclusion:RA likely play an important role in thymocytes development, perhaps by affecting the relative expression of RAR gene.