INTERFERON IN SYSTEMIC LUPUS ERYTHEMATOSUS

ABSTRACT Many patients with systemic lupus erythematosus (SLE) have high concentrations of interferon (IFN) in their serum. The IFN was shown to be human leukocyte, or alpha, IFN by neutralization with specific anti-IFN antisera, antiviral activity on bovine cells and affinity column chromatography. However, unlike reference human alpha IFN, the alpha IFN from SLE patients was inactivated at pH 2, and appears to be a previously undescribed subspecies of alpha IFN. Serial IFN samples from the same patient had similar biological properties, but IFNs from different SLE patients were not all identical. Although patients with active disease were more likely to be IFN-positive than patients with disease in remission, there was no correlation between any individual clinical or serologic marker of SLE and the presence of circulating IFN. Mononuclear cells isolated from IFN-positive SLE patients did not spontaneously secrete IFN in culture. Cells stimulated with mitogens produced gamma IFN, and cells stimulated with UV-inactivated NDV produced a conventional mixture of acid-stable alpha IFNs. The cellular source and inducing agent(s) of the pH 2 labile alpha IFN present in serum of SLE patients are still unknown.