REDUCED SERUM LEVEL OF TRANSFORMING GROWTH-FACTOR-BETA IN PATIENTS WITH IGA DEFICIENCY

Seventeen patients with IgA deficiency, 13 subjects with selective IgA deficiency and 4 with a combined IgA and IgGB deficiency, were assess ed for serum levels of cytokines relevant for B cell differentiation. Transforming growth factor (TGF)-beta was quantified by bioassay and i nterleukin (IL)-4, IL-6, and IL-7 by immunoassay, The serum levels of TGF-beta were significantly lower in patients with IgA deficiency than in healthy blood donors, Of the patients with IgA deficiency, 4 had d etectable IL-4 levels while 4 of the others had detectable IL-6 levels in serum. IL-4 and IL-6 were not detected in the controls. Serum IL-7 levels were similar in patients and controls. A significant, negative correlation was found between serum TGF-beta and the number of circul ating B lymphocytes in the patients with IgA deficiency. No associatio n was found between serum cytokine levels and the occurrence of infect ions at the time of study, Since TGF-beta has been implicated in IgA i sotype switching in man, and our study demonstrates an association bet ween low serum TGF-beta levels and IgA deficiency, dysregulation of TG F-beta might be a contributing factor in the pathogenesis of IgA defic iency. (C) 1995 academic Press, Inc.