Function of lymphocytes and monocytes in silicosis

The function of lymphocytes and monocytes was compared in a group of 18 ex-sandblasters with silicosis and 19 control subjects. Previously noted depressed lymphocytic proliferation in response to low concentrations of concanavalin A (ConA) in subjects with silicosis was not due to factors in the serum nor correctable by supplementation with allogeneic lymphocytes. Monocytes from the peripheral blood of the subjects with silicosis responded less to a chemotactic stimulus (zymosan-activated serum) than did monocytes from normal laboratory personnel; however, there was no difference in monocytic chemotaxis when groups of similar age were compared. There was a significant correlation between age and the monocytic response to chemotactic stimuli in the studied population (laboratory personnel, silicotic subjects, and age-matched control subjects). Overall, our data suggest subtle effects of silica on selected T-lymphocytic populations involved with responsiveness to the mitogen, concanavalin A, but no effects on monocytic function. Monocytic chemotaxis is unaffected by exposure to silica but is inversely related to age.