摘要Serum IgA, IgG, IgM, C 3 CH 50, RF, ANF and the percentage of rosette-forming cells in peripheral lymphocytes are determined in specimens collected from patients with chronic bronchitis and normal controls. It is shown that the patients have a tendency to a reduction in percentage of peripheral T-lymphocytes, increase in levels of IgG and IgA, decrease in serum complement activity and appearance of RF and ANF. The positive correlation between the increasing levels of IgG and IgA, RF positive rate, 24-hr sputum DNA-concentration and sera bacterial antibody titers suggest the importance of respiratory tract bacterial infection in RF pathogenesis and increasing immunoglobulin levels. Whether the declined serum complement activity is due to infection or autoimmune mechanism is still unknown.