Objective：To explore the changes and significances of cellular immunity in the occurrence and development of chronic ob－structive pulmonary disease（COPD）. Methods：Flow cytometry was used to detect the changes of CD3+，CD4 +，CD8+ T cells，CD19+ B cells and CD16+56+ natural killer（ＮＫ） cells in peripheral blood of 31 normal controls，35 patients at remission stage and 29 patients at acute severe stage. Correlation of these changes with smoking index，hospital duration and disease course was analyzed. Results：①CD3+ T cell and CD4+ T cell counts were decreased significantly in patients at remission stage and acute severe stage than in normal controls；CD4+/CD8+ was decreased significantly and CD16+56+ NK cells were increased significantly in patients at acute severe stage. ②CD4+ T cell count was decreased significantly and CD16+56+ NK cell count was increased significantly in patients at acute severe stage than in those at remission stage.③CD3+CD4+ T cells were negatively correlated with smoking index；hospital duration was nega－tively correlated with CD3+CD4+ T cells and CD4+/CD8+，but was positively correlated with CD3+CD8+ T cells and CD16+56+ NK cells. Conclusions：CD3+CD4+ T cells play an important role in the pathogenesis of COPD and are closely related with the onset，severity and treatment of COPD. CD4+/CD8+，CD16+56+ NK cells are closely related with the acute attack and treatment of COPD.
