EXPRESSION OF THE COMPLEMENT REGULATORY PROTEINS DECAY-ACCELERATING FACTOR (DAF, CD55), MEMBRANE COFACTOR PROTEIN (MCP, CD46) AND CD59 IN THE NORMAL HUMAN UTERINE CERVIX AND IN PREMALIGNANT AND MALIGNANT CERVICAL DISEASE

The membrane-bound complement regulators decay-accelerating factor (DA F, CD55), membrane cofactor protein (MCP, CD46), and CD59 are broadly expressed proteins that act together to protect host tissues from auto logous complement. Comparison of expression profiles of these proteins between normal and pathological tissues could reveal a mechanism by w hich tumor cells evade complement-mediated killing, Expression of the regulators was therefore examined in the normal human uterine cervix, in cervical intraepithelial neoplasia (CIN; n = 23), and in cervical s quamous carcinomas (n = 6), DAF and MCP were reciprocally expressed in normal ectocervical epithelium. MCP was confined predominantly to the basal and parabasal layers with more extensive expression in metaplas tic squamous epithelium. An apparent expansion in MCP expression was o bserved in more severe premalignant lesions whereas cervical carcinoma s were uniformly MCP positive. By contrast, DAF expression appeared un altered in premalignant lesions and variable in carcinomas. However, i ncreased DAF was observed in stromal cells directly adjacent to infilt rating tumor cells. A low molecular weight DAF product was detected in tumors, and preliminary evidence suggests this may be derived from st romal cells, Overall, changes in expression of C3 convertase regulator s in both the stromal and epithelial compartments may be important for evasion of immune surveillance in cervical cancer.