ANTIBODIES REACTIVE WITH THE PROTEIN CORE OF MUC1 MUCIN ARE PRESENT IN OVARIAN-CANCER PATIENTS AND HEALTHY WOMEN

Antibodies reactive with peptide epitopes on the core protein of MUC1 epithelial mucin have been demonstrated in some patients with adenocar cinomas. Because these epitopes can be exposed on MUC1 in the serum of healthy women, we measured concentrations of MUC1-reactive antibodies in the serum of healthy pregnant and non-pregnant women, and in patie nts with benign and malignant ovarian tumours. Antibodies were measure d in an enzyme-linked immunosorbent assay utilising a synthetic peptid e corresponding to a 105-amino-acid segment of the MUC1 tandem repeat region (5.25 repeats). MUC1-reactive antibodies were always of an IgM isotype and concentrations were highest in young healthy women and dec lined progressively with age (P = 0.0006) concomitantly with increasin g serum MUC1 levels (P = 0.003). Regardless of age, antibody levels we re lower in cancer patients than in healthy women (P<0.0001), but MUC1 levels were much higher in cancer patients (P<0.0001). Although high antibody levels were associated with greater survival in ovarian cance r (P = 0.015), multivariate regression analysis showed that this was n ot a significant independent prognostic indicator after consideration of the International Federation of Gynaecology and Obstetrics (FIGO) s tage, histological type, serum MUC1 levels and age. Serial measurement of MUC1 and MUC1 antibodies during treatment in 18 patients with ovar ian cancer and throughout pregnancy in 10 women showed a negative corr elation between alterations in MUC1 and MUC1 antibodies. These results show that MUC1-peptide-reactive antibodies are present in the serum o f healthy women and women with cancer and that they probably form immu ne complexes with MUC1, but provide no evidence for an augmentation of the humoral immune response to MUC1 in ovarian cancer.