Changes of regulatory B cells in patients with acute Kawasaki disease and its significance

Abstract

Objective To investigate the role of regulatory B cells （ Breg ） in the immunological pathogenesis of Kawasaki disease （ KD） .Methods Twenty-eight children with acute KD and twenty-eight age-matched healthy subjects were enrolled in this study .Blood samples were collected before and after the treatment of intravenous immunoglobulin （IVIG）.The proportions of CD19＋CD24hiCD38hi Breg and CD4＋CD25＋Foxp3＋regulatory T cells （Treg）, and the expressions of co-stimulatory molecules （CD80, CD86 and PD-L1） were analyzed by flow cytometry .The concentration of IL-10 protein was measured by enzyme-linked immunosorbent assay .Real-time PCR was performed to evaluate the expressions of Foxp 3, CTLA4 and GITR in CD4＋T cells and IL-10 in CD19＋B cells at mRNA level.Results （1） The proportions of CD19＋CD24hi CD38hi Breg in peripheral blood and the expressions of IL-10 at mRNA level in CD19＋B cells from patients with KD were lower than those from healthy controls （P〈0.05）, but significantly increased after treated with IVIG （P〈0.05）.Upon stimulation of lipopolysaccharide for 48 hours, the concentrations of IL-10 protein in culture supernatant of B cells from patients with KD were still lower than those from healthy controls [（31.06±8.26） pg/ml vs.（46.32±13.91） pg/ml, P〈0.05].（2） Compared with healthy controls , the expressions of CD80, CD86 and PD-L1 were remarkably down-regulated in patients with acute KD （ P〈0.05）.With the treatment of IVIG, the expressions of CD80 and CD86 were significantly up-regulated though lower than those of the control group （P〈0.05）.There was no significant difference in the expression of PD-L1 before and after treatment （P〉0.05）.（3） The proportions of CD4＋CD25＋Foxp3＋Treg and the expressions of Foxp3, CTLA-4 and GITR at mRNA level were significantly decreased in KD group compared with those in control group （P〈0.05）, but were increased to some extent after IVIG treatment （P〈0.05）. In addition, a positive correlation between the proportion of CD 19＋CD24hiCD38hi Breg and the proportion of CD4＋CD25＋Foxp3＋Treg was found in patient with acute KD （r=0.62, P〈0.05）.Conclusion Breg cell deficiency and its impaired function might be one of the important factors causing immune dysfunction in pa -tients with acute KD . Key words: Regulatory B cells; Kawasaki disease; Co-stimulatory molecule; IL-10; Regulatory Tcells