HUMAN-COMPLEMENT REGULATOR EXPRESSION BY THE NORMAL FEMALE REPRODUCTIVE-TRACT

Background: The membrane-associated proteins that regulate human compl ement activation are ubiquitously expressed and function cooperatively to protect cells from autologous complement damage. For classical and alternative pathways, the primary regulators at the stage of C3 prote olysis and deposition are membrane cofactor protein (MCP; CD46) and de cay-accelerating factor (DAF;CD55), whereas protectin or CD59 regulate s terminal component assembly. There is increasing awareness in reprod uctive, tumor, and transplantation immunology of the conventional and non-complement roles of these proteins. The human reproductive system may serve as a model of the non-complement functions. Methods: We perf ormed immunohistochemical analyses of multiple normal ovaries, fallopi an tubes, cervices, and uterine corpi by using well-characterized mono clonal antibodies to provide a detailed, direct comparison of compleme nt regulator expression. Results: Membrane cofactor protein was diffus ely and strongly expressed on all epithelia and vascular endothelium a nd was the predominant regulator on oocytes. In contrast, decay-accele rating factor had variable expression in intensity and distribution on epithelia and was notably absent on certain epithelia and oocytes. It was the only regulator present on the connective tissue between muscl e bundles in the myometrium and the cervix and was found on most strom a. CD59, although staining intensity varied, was present on virtually all epithelia, vascular tissue, and stroma. Conclusions: Distinct repr oducible patterns of complement regulator expression are found through out the female reproductive tract. Differential expression on certain epithelia and oocytes may suggest non-complement activities. This comp rehensive study should provide a basis for further characterization of pathological tissues and mechanisms of cellular localization. (C) 199 6 Wiley-Liss, Inc.