Characteristics and clustering analysis of peripheral blood lymphocyte subsets in children with systemic lupus erythematosus complicated with clinical infection

Objectives Clinical infection is a common complication in children with systemic lupus erythematosus (SLE). However, few studies have investigated immune alterations in children with SLE complicated with clinical infection. We assessed lymphocyte subsets in children with SLE to explore the possibility of clinical infection. Methods We retrospectively analyzed the proportion of peripheral lymphocyte subsets in 140 children with SLE. Children with SLE were classified into different clusters according to the proportion of peripheral blood lymphocyte subsets: (CD3 + /CD4 + T cell, CD3 + /CD8 + T cell, CD3 + /CD4 + /CD8 + T cell, CD3 + /CD4-/CD8- T cell, CD19 + B cell, and CD3-/CD16 + /CD56 + NK cell). Differences in the proportion of lymphoid subsets, infection rates, and systemic lupus erythematosus disease activity index (SLEDAI) scores were compared between clusters. In addition, we grouped the subjects according to the presence or absence of infection. Proportions of lymphoid subsets, demographic variables, clinical presentation, and other laboratory variables were compared between the infected and uninfected groups. Finally, the diagnostic ability of lymphocyte subset ratios to distinguish secondary infection in children with SLE was predicted using an ROC curve. Results Cluster C2 had a higher proportion of B cells than Cluster C1, while Cluster C1 had a lower proportion of NK cells, CD3 + T cells, CD3 + /CD4 + T cells, CD3 + /CD8 + T cells, and CD3 + /CD4-/CD8- T cells. Infection rates and SLEDAI scores were higher in Cluster C2 than in Cluster C1. The infected children had a higher proportion of B cells and a lower proportion of CD3 + T cells, CD3 + /CD4 + T cells, CD3 + /CD8 + T cells, and CD3 + /CD4-/CD8- T cells. There were no significant differences in lymphoid subsets between children in Cluster C2 and the infected groups. The area under the ROC curve of B lymphocytes in predicting SLE children with infection was 0.842. The area under the ROC curve was 0.855 when a combination of B cells, NK cells, CD4 + T cells, and CD8 + T cells was used to predict the outcome of coinfection. Conclusions A high percentage of B cells and a low percentage of CD3 + T cells, CD3 + /CD4 + T cells, CD3 + /CD8 + T cells, CD3 + /CD4 + /CD8 + T cells, and CD3 + /CD4-/CD8- T cells may be associated with infection in children with SLE. B cells was used to predict the outcome of coinfection in children with SLE. Key Points • A high percentage of B cells and a low percentag