Impaired antibody-dependent cell-mediated cytotoxicity in cryptogenic fibrosing alveolitis (synonym: idiopathic pulmonary fibrosis).

Mononuclear cells from the blood of 26 patients with the 'autoimmune' connective tissue disorder cryptogenic fibrosing alveolitis (CFA) were examined in Chang cell cytotoxicity assays for their capacity to mediate antibody-dependent cell-mediated cytotoxicity (ADCC). The results showed an impairment for the group by comparison with a group of 45 normal healthy controls (P less than 0.01). The impairment was greater in patients with associated connective tissue disorders of other systems (CFA+CT) than in those having the lung disorder alone (lone CFA); (P less than 0.001). The reduction in ADCC showed a correlation with reducing counts of cells bearing Fc gamma G surface receptors (P less than 0.05), and with increasing levels of soluble immune complexes in the blood of these patients by C1q binding (P=0.05). Non-specific esterase staining indicated that the Fc gamma G rosetting cells were subpopulations of lymphocytes not monocytes. We therefore suggest that the observed ADCC impairment may be due to impairment of lymphocyte Fc receptor function, and we speculate that this may influence immune regulation.