Abstract: Objective　To investigate the clinical significance of sphingomyelinase（sMase）and tumor necrosis factor-alpha（TNF-α）in patients with rheumatoid arthritis（RA）and atherosclerosis（AS）. Methods　The cultured human umbilical cord vein vascular endothelial cells（EC）were stimulated by TNF-α， and the activity of sMase in the supernatant was detected. The serum sMase activity and TNF-α levels were detected in 124 RA patients [66 patients with only RA and 58 RA patients also with coronary heart disease（CHD）] and the corresponding control group. Results　The sMase activity of EC increased significantly after the stimulation of TNF-α. The serum sMase activity of RA group was higher than that of control group，especially the activity of RA combined CHD group was the highest. The serum TNF-α levels of only RA group and RA combined CHD group were higher than that of control group. Conclusions　The sMase activity of EC increases with the stimulation of TNF-α. The increases of TNF-α level and sMase activity in RA patients are related to vascular endothelial damage. Therefore，sMase activity may become one of the laboratory diagnostic indicators of vascular endothelial cell dysfunction（ECD）.

Key words: Sphingomyelinase, Tumor necrosis factor-alpha, Rheumatoid arthritis