Purification of inhibin from human follicular fluid using monoclonal antibody

Background: Inhibin is a protein synthesized by granulosa and sertoli cells which preferentially inhibit pituitary secretion of FSH through a negative-feedback. Studies have showed that measurement of inhibin has a clinical role in understanding the fertility status of men and women and could also be used as a prognostic marker for pre-eclampsia and Down syndrome in fetus. There are many different multi-step procedures for the purification of inhibin. In this study we attempted to purify inhibin from human follicular fluid using immunoaffinity techniques. Materials and Methods: Follicular fluid (FF) collected from women referring to Avicenna Infertility Clinic, was filtrated and subsequently concentrated by ammonium sulfate. The presence of inhibin in follicular fluid was detected using enzyme-linked immunosorbent assay . In order to purify inhibin, an affinity chromatography column using anti-inhibin monoclonal antibody was prepared. The purified protein was analyzed through SDS-PAGE and western blotting after a protein solution load of human inhibin into the column. Results: The SDS-PAGE results of affinity proved the presence of inhibin following silver staining appeared as a single 32 kDa band . Western blotting revealed that specific anti-inhibin antibody was able to recognize inhibin epitopes. The present protocol for purification of inhibin is a technique with 92% yield. Conclusion: This method is a sensitive procedure for high yielded productions of inhibin compared to the previously described methods, using HPLC and gel filtration. However, since preparing and obtaining follicular fluid, as a main source of inhibin, is rather difficult but suitable for laboratories, recombinant inhibin is recommended for mass production.