INDUCTION OF IMMUNE-RESPONSES TO OVARIAN TUMOR-ANTIGENS BY MULTIPARITY

OBJECTIVE: Because epidemiologic data indicate a reduction in ovarian cancer risk with increased parity, the occurrence of maternal immuniza tion against ovarian tumor-associated antigens during pregnancy was in vestigated. METHODS: Sera were obtained from nulligravid and multiparo us women and from men. Cellular proteins were isolated from four ovari an tumor cell lines as well as from normal ovaries. These proteins wer e separated by sodium dodecyl sulfate-polyacrylamide gel electrophores is, and the presence of cellular proteins reactive with each individua l's serum was assessed by Western immunoblot. Tumor-reactive antibodie s from two multiparous women were used to prepare immunoaffinity colum ns for the isolation of reactive proteins from ovarian tumor cells. Th ese immunoaffinity-purified antigens were transferred electrophoretica lly to nitrocellulose membranes, stained with Ponceau S, and identifie d by amino acid sequencing. RESULTS: Western immunoblot analysis of th e cellular proteins from four established ovarian tumor cell lines usi ng sera from multiparous women as the primary antibody indicated that these samples recognized multiple bands on ovarian tumors, ranging fro m 30 to 150 kD. Two commonly recognized proteins were isolated and sub jected to microsequencing, which identified the 56-kD band protein as elongation factor-1 alpha and the 38-kD protein as nucleophosmin/B23 p rotein. Both of these proteins play integral roles in cell growth. CON CLUSION: These findings suggest that certain antigens expressed by the fetus immunize women during pregnancy. This immune response may prote ct these women from the subsequent development of cancer. Copyright (C ) 1997 by the Society for Gynecologic Investigation.