High levels of naturally occurring IgG antibodies to mucin 1 (MUC1), a membrane-bound glycoprotein that is overexpressed in patients with breast cancer, are associated with good prognosis. This suggests that endogenous anti-MUC1 antibodies have a protective effect and, through antibody-mediated host immunosurveillance mechanisms, might contribute to a cancer-free state. To test this possibility, we characterized a large number of multiethnic patients with breast cancer and matched controls for IgG antibodies to MUC1. We also aimed to determine whether the magnitude of anti-MUC1 antibody responsiveness was associated with particular immunoglobulin GM (γ marker), KM (κ marker), and Fcγ receptors (FcγR) genotypes. After adjusting for the confounding variables in a multivariate analysis, we found no significant difference in the levels of anti-MUC1 IgG antibodies between patients and cancer-free controls. However, in patients and controls, particular GM, KM, and FcγR genotypes-individually or epistatically-were significantly associated with the levels of anti-MUC1 IgG antibodies in a racially restricted manner. These findings, if confirmed in an independent investigation, could help identify individuals most likely to benefit from a MUC1-based therapeutic or prophylactic vaccine for MUC1-overexpressing malignancies.
Keywords: FcγR genes; GM/KM allotypes; Humoral immunity; MUC1.
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