Human macrophage function in cancer: systemic and local changes detected by an assay for Fc receptor expression

The activity of human peripheral blood monocytes and pulmonary alveolar macrophages was examined with a rosette assay that detects changes in Fc receptor expression. Compared with peripheral blood monocytes from normal subjects, the peripheral blood monocytes of patients with carcinoma of the lung were found to be activated in this respect. In contrast, compared with pulmonary alveolar macrophages from normal subjects, carcinomas exhibited depressed function in terms of receptor alveolar macrophages from lungs bearing primary expression. Trypsinization of macrophages to remove bound immunoglobulin indicated that this depression of receptor activity was not due to blocking of receptors by immunoglobulin or immune complexes. In an in vitro study the expression of Fc receptors by cultured macrophages was shown to be depressed by a heat-stable, low-molecular-weight material in supernatants of cultured carcinoma tissue from the lung, breast, and urinary bladder.