To elucidate possible association of silicosis with monoclonal gammopathy, serum protein was electrophoretically analized in 616 cases with silicosis. As reusults, monoclonal proteins (M-proteins) were shown in 15 cases (2.4%). One case was diagnosed IgA multiple myeloma, the other 14 cases, benign monoclonal gammopathy. The frequency of M-proteins among cases with silicosis at present study was significantly higher than those found in normal indivisual groups. The class of M-protein was IgA in 8 cases (53%), IgG in 5 cases (33%) and IgM in 2 cases (13%). The incidence of IgA M-proteins was relatively high. These clinical observations suggest that the protracted stimulation of immune system by silica containing adjuvant effect may be implicated in pathogenesis of monoclonal gammopathy.
