ASSOCIATION OF CIRCULATING RECEPTOR FC-GAMMA-RIII-POSITIVE MONOCYTES IN AIDS PATIENTS WITH ELEVATED LEVELS OF TRANSFORMING GROWTH-FACTOR-BETA

Monocytes in the circulation of normal individuals express two receptors for the constant region of immunoglobulin, Fc-gamma-RI and Fc-gamma-RII. In contrast, we have observed that AIDS monocytes express significant levels of a third Fc-gamma-R, Fc-gamma-RIII (CD16), which is normally associated with activation or maturation of the monocyte population. By dual-fluorescence analysis using a monoclonal antibody specific for Fc-gamma-RIII (MAb 3G8), 38.5 +/- 3.2% of the LeuM3 (CD14)-positive monocytes in AIDS patients were CD16 positive as compared to 10.4 +/- 1.0% for healthy individuals (n = 29; P < 0.005). Furthermore, AIDS monocytes expressed Fc-gamma-RIII-specific mRNA which is expressed minimally or not at all in control monocytes. As a recently identified inducer of Fc-gamma-RIII expression on blood monocytes, transforming growth factor-beta (TGF-beta) was found to be elevated in the serum and/or plasma of AIDS patients. Moreover, incubation of normal monocytes with AIDS serum or plasma induced CD16 expression which correlated with serum TGF-beta levels (r = 0.74, P < 0.001) and was inhibited with a neutralizing antibody to TGF-beta. Thus, the increased CD16 expression on peripheral blood monocytes in AIDS patients may be the consequence of elevated circulating levels of the polypeptide hormone TGF-beta.