To investigate the characteristic of lymphoctye subsets of patients with systemic lupus erythematosus (SLE) in different status of cytomegalovirus (CMV) infection and to provide new basis for clinical diagnosis of SLE.

Total of 96 inpatients with SLE admitted to Zhangjiagang Hospital Affiliated to Nanjing University of Chinese Medicine from June 2016 to June 2019 were selected, including 18 patients with cytomegaloviremia (cytomegaloviremia group), 50 patients with cytomegalovirus disease (cytomegalovirus disease group), and 28 patients without CMV infection (control group). General clinical data, routine laboratory indicators, CMV DNA copies and peripheral blood lymphocyte subsets of the three groups were analyzed, respectively. The above indicators were compared among patients with different CMV infection status, and the characteristics of lymphocyte subsets in different status of CMV infection were analyzed.

The erythrocyte sedimentation rate (t =-0.141, P = 0.025; t =-0.194, P = 0.003) of cytomegaloviremia group and cytomegalovirus disease group were significantly higher than those of control group and CRP level of cytomegalovirus disease group was significantly higher than that of control group (t =-0.854, P = 0.006). The cases treated with cyclophosphamide (χ² =-6.139, P = 0.013) and the copies of CMV DNA in blood (t =-0.355, P = 0.041) in cytomegalovirus disease group were significantly higher than those of cytomegaloviremia group, all with significant differences. There were no significant differences in total lymphocyte count, CD3⁺ T cells, CD3⁺CD4⁺T cells, CD3⁺CD8⁺ T cells, CD19⁺ B cells and CD56⁺CD16⁺ NK cells between the cytomegaloviremia group and the control group (all P > 0.05). Total lymphocyte count (t = 0.933, P < 0.001), CD3⁺ T cells (t = 0.177, P < 0.001), CD3⁺CD4⁺ T cells (t = 0.207, P < 0.001), CD3⁺CD8⁺ T cells (t = 0.169, P < 0.001) and CD19⁺ B cells (t = 0.320, P = 0.023) were significantly lower in patients with cytomegalovirus disease than those of control group.

Low lymphocyte count (especially CD4⁺ T cell count) was common in patients with SLE complicated with CMV infection, which was a potential biomarker for the diagnosis of CMV infection in patients with SLE.