Expression of major histocompatibility antigens and nature of inflammatory cellular infiltrate in ovarian neoplasms

Expression of histocompatibility antigens and the intensity of inflammatory cellular infiltrate were evaluated in frozen tissue sections from 70 human ovarian tumors and six normal ovaries using monoclonal antibodies and an avidin‐biotin immunoperoxidase technique. In the normal human ovary, surface epithelial cells, mature granulosa cells and lutein cells reacted with anti‐HLA‐A, B, C (HLA) and beta₂‐microglobulin antibodies but not with anti‐la (la‐like, HLA‐DR). Stromal cells and granulosa cells of the primordial follicles did not react with any of the antibodies. Among the neoplasms examined, all benign epithelial tumors, 86% of borderline an 81% of malignant epithelial tumors reacted with anti‐HLA and/or beta₂‐microglobulin antibodies. HLA‐negative epithelial tumors were of serous or endometrioid types. Although la was not found in normal ovarian surface epithelium, the antigen could be detected in 44% of benign, and 43% of borderline and malignant epithelial ovarian tumors. Mono‐nuclear cellular infiltrate was generally scarce in ovarian tumors and consisted mainly of T cells. Malignant epithelial tumors contained significantly more T cells than did benign tumors. More T cells were observed in HLA‐positive ovarian tumors than in HLA‐negative neoplasms, but the difference did not achieve statistical significance. No correlation could be found between la expression and the intensity of T‐cell infiltrate. Significantly more T8 and Leu‐3a‐positive cells were found in the tumor stroma than amongst neoplastic cells. HNK‐I‐positive natural killer cells, OK‐MI‐positive macrophages and BI‐positive B lymphocytes were rarely encountered either in the tumor stroma or between adjacent tumor cells.