CD38 and systemic lupus erythematosus: Interestingly the ratio of CD4+CD25+DR+/CD4+CD38+DR+ cells was significantly higher in thrombotic APS patients as compared with disease control groups (1.3 ± 0.5, 0.83 ± 0.4, and 0.59 ± 0.36 in APS patients, aPL positive controls, and SLE patients, resp., P = 0.004).