p53 autoantibodies in patients with autoimmune diseases: a quantitative approach.

With few exceptions, autoantibodies directed against the gene product of the tumor suppressor gene p53 are only detected in cancer patients. From 73 patients with various autoimmune diseases, we obtained 17 sera with elevated autoantibodies against the p53 protein comprising patients with SLE, Graves' disease, and immune vasculitis including Wegener's granulomatosis. The overall prevalence (23%) of p53 autoantibodies was comparable to that in various cancers; differences, however, were obvious with respect to the magnitude of antibody levels. Only 5% of seropositive colorectal cancer patients had levels within the critical range (150-180 U/ml) but nearly half (41%) of seropositive autoimmune disease patients were that low. None of the autoimmune disease patients exceeded 300 U/ml serum compared to more than 60% of seropositive colorectal cancer patients with higher levels. This remarkable difference in magnitude underlines the necessity of quantification of p53 autoantibodies over a mere qualitative determination. Patients with autoimmune diseases face an increased risk for malignancies. It still remains to be established whether p53 seropositivity in autoimmune diseases adds to the rare exceptions of p53AAb in non-malignant diseases or is indicative for a yet occult cancer.