Abstract: Objective To investigate the effect of CD40/CD40 ligand on the genesis and development of coronary artery disease (CAD)， and the inhibitory effect of cyclosporine A (CsA) on CD40/CD40 ligand. Methods A total of 71 patients were divided into four groups: acute myocardial infarction group (AMI, n=19), unstable angina pectoris group (UAP, n=18), stable angina pectoris group (SAP, n=17) and normal control group (N, n=17). Flow cytometry was used to detect the expression of CD40 and CD40L in peripheral blood mononuclear cells (PBMCs) of four groups. The group in which CD40 and CD40L were produced at the highest level was chosen, and a series concentrations of CsA（H1:0 mg/L, H2:0.01 mg/ L, H3: 0.1 mg/L, H4:1 mg/L） were used to treat the cells. Then the expressions of CD40 and CD40L were measured by flow cytometry. Results Compared with N group， the expression of CD40 was significant higher in other groups (P < 0.05). The expression of CD40 was significant higher in UAP group and AMI group than that of SAP group. There was no significant difference in the expression of CD40 between UAP group and AMI group (P > 0.05). The expression of CD40L was elevated and fol⁃ lowed by different severity of CAD. There was significant difference in the expression of CD40L between groups (P < 0.05) . AMI group showed the highest expression of CD40 and CD40L. After being treated with CsA, the expression of CD40 was higher in H1 group than that of H3 group and H4 group (P < 0.05). The expression of CD40L was significantly higher in H1 group than that of other three groups (P < 0.05). Conclusion CD40 and CD40L may be involved in the development of CAD. Moreover, it might be restrained by CsA via regulation of CD40/CD40L.

Key words: coronary artery disease, cyclosporine A, antigens, CD40, CD40 ligand, flow cytometry