To gain insight into the immuno-pathogenesis of drug-induced autoimmune disorders, lymphocyte and immunoglobulin distributions and cytokine levels were monitored in the peripheral blood and pleural fluid of a patient with procainamide-induced lupus and pleural effusion. Approximately 80% of the B cells in both compartments were CD5+ compared to 10% to 25% in normal adults. CD4/CD8 ratio and percentage CD4 were normal in peripheral blood. Serum levels of IgG (particularly IgG2), IL-6, and soluble IL-2R were slightly elevated, and those of IgA were significantly elevated compared to normal controls. Analysis of the pleural effusion revealed an increased CD4/CD8 ratio because of an increased percentage of CD4+CD29+ helper memory T cells, lack of expression of the resting B-cell marker CD21, immune complex deposition and complement consumption, increased relative levels of ANA, abnormally high levels of IL-6 and soluble IL-2R, and detectable levels of IL-1b, IFN-g and TNF-a. These observations provide evidence for the involvement of CD5+ B cells and differential helper T-cell activity in procainamide-induced lupus and for an association between local lymphocyte activation and organ pathology.
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