GONADOTROPIN-RELEASING HORMONE TYPE-I (GNRH-I) EXPRESSION IN PERIPHERAL LYMPHOCYTES AND POSSIBLE IMMUNE ACTION* Periferik lenfositlerde gonadotropin-releasing hormon tip-I (GnRH-I) ekspresyonu ve muhtemel immün etki

Purpose: Expression of GnRH receptor type-I (GnRHR) and GnRH-I are not restricted to the hypothalamic area, and have been demonstrated in the immune system. GnRH expression in human B lymphocytes has not yet been explored. We therefore investigated GnRH-I expression in human peripheral mononuclear blood cells (PMBC) and B lymphoblastoid cells (B-LCLs). We also investigated the regulation of B-LCL proliferation by GnRH in the presence and absence of interleukin-2 (IL2). In the present study, we report the preliminary results from our ongoing collaborative study. Materials and Method: RT-PCR was used for expression of locally produced GnRH-I. The effects of GnRH-I on BLCL proliferation were investigated using a nonradioactive cell proliferation assay. Results: GnRH-I was present in PMBC and in B lymphocyte groups (normal and GnRHR defective BLCLs). Treatment of normal B-LCLs with GnRH and with Interleukin-2 (IL-2) resulted in a significant increase in proliferation compared with the untreated control (p<0.05). Normal B-LCLs co-treated with IL-2 and GnRH demonstrated higher proliferative responses than IL-2 treatment alone. In GnRHR defective B-LCLs, there were no significant proliferative responses to either GnRH or IL-2 treatment, nor to IL-2 and GnRH cotreatment when compared to controls. Conclusion: We therefore confirm the presence of GnRH transcript in PMBC and B-LCLs. GnRH induced a proliferative response in B-LCLs, an effect mediated by a functional GnRHR. Furthermore, the IL-2 mediated proliferative response in B lymphocytes is modulated by GnRH. Further experimental data are necessary to understand the physiological effects of local GnRH in the immune system.