Cell-mediated immunity in silicosis.

Selected parameters of cell-mediated immunity were determined in a group of 16 patients with silicosis. The results were compared with those of a control group of 13 subjects without silica exposure. There were no group differences in the mean number of delayed hypersensitivity skin tests to a battery of recall antigens (purified protein derivative, candida, streptokinase-streptodornase, and trichophyton) or in the mean number of peripheral blood lymphocytes. Lymphocyte responsiveness to phytohemagglutinin, pokeweed mitogen, and the antigens listed, and the percentage of lymphocytes that formed sheep red blood cell rosettes (t cells) and complement rosettes (B cells) were also similar in both groups; however, the silica-exposed group demonstrated depressed lymphocyte stimulation in response to low concentrations of concanavalin A.