Diminished suppressor cell function in patients with asbestosis

Epidemiological and immunological studies of asbestos workers documented abnormalities in humoral and cell-mediated immunity which could result from defective immunoregulation. This study tests this hypothesis with comparison of lymphocyte function in age-, sex- and smoking-matched subjects with asbestosis. In vivo measure of delayed hypersensitivity (i.e. skin test response) was significantly depressed to two recall antigens, SKSD and Candida, in asbestosis patients. Skin reaction to dinitrochlorobenzene (DNCB) was not depressed, although lymphocytes of patients giving positive skin test reactions demonstrated a significantly lower (P less than 0.001) proliferative response to dinitrobenzene sulphonic acid (DNBSO3) in vitro. T cell counts (E-rosettes) were normal in patients with asbestosis, although a subset of T cells, those forming sheep erythrocyte rosettes after prolonged incubation (Elate), were significantly depressed (P less than 0.003). This population has been equated with 'suppressor' cells (Grossi et al., 1978). Numbers of B cells were increased nearly two-fold over controls. Mitogen response of lymphocytes was normal except at suboptimal doses of mitogens where the response is known to be influenced by suppressor cell activity, which was significantly elevated. Suppressor cell function, as determined by stimulation of peripheral blood lymphocytes preincubated with concanavalin A, was also significantly decreased in asbestosis patients (P less than 0.01).