Hormonal regulation and convertase activities of complement 3 in human oviductal epithelial cells

Abstract

Human oviduct cells produce complement 3 (C3). The derivative of C3, iC3b, but not C3 enhanced mouse preimplantation embryo development. We hypothesized that the human oviduct uses the complement pathways for complement activation to convert C3 to iC3b via C3b and that production of C3 in the oviducts is under hormonal regulation. The aim of this study is to investigate the effect of hormones on C3 mRNA expression and the conversion of C3 into C3b/iC3b in the human oviductal epithelial cells (OE). In vitro cultured primary OE cells were treated with varies concentrations of estrogen and progesterone either alone or in combination. Estrogen enhanced C3 mRNA expression of OE cells. Progesterone alone has no effect on C3 expression. The presence of the components of C3 convertases were studied by RT-PCR and immunocytochemistry, respectively. Molecules involved in complement activation, C2 and C4 in the classical pathway and lectin pathway, and factor B (fB) and factor D (fD) in the alternative pathway was detected in the OE cells. The OE cell culture possessed active C3 convertase that converted exogenous C3 into C3b in a time-dependent manner. No iC3b was produced under this condition. In conclusion, the production of C3 in oviduct is estrogen-regulated and the oviductal cells can convert C3 toC3b but not iC3b.