Expressions and clinical significance of inducible co-stimulator and inducible co-stimulator ligand in peripheral blood of patients with systemic lupus erythematosus

Abstract

Objective To investigate the expression of inducible co-stimulator (ICOS) and inducible costimulator ligand (ICOSL) on PBMCs, and the plasma concentrations of soluble forms of ICOSL and their clinical relationship with systemic lupus erythematosus(SLE) patients. Methods Peripheral blood samples were collected from 45 SLE patients and 39 healthy subjects(HC). The expressions of ICOS and ICOSL on peripheral blood mononuclear cells (PBMCs) were detected by flow cytometry. The concentrations of soluble ICOSL were assessed by measured by enzyme linked immunosorbent assay (ELISA). And the relationship bet-ween their expression levels and patients' clinical manifestations were analyzed. Levene F test was used for statistical analysis, the comparison between groups was conducted using t test, and the correlation between two variables were tested by Pearson correlation analysis. Results The expression of ICOS on CD4+ and CD8+ T cells were significantly higher than that of the HC [(19.1±1.7)% vs(14.0±1.5)%, t=2.156, P=0.035], [(10.0±1.0)% vs (6.4± 1.0)%, t=2.587, P=0.012]. The expression of ICOSL on CD14 + mononuclear cells in SLE patients was significantly higher than that in the HC group[(2.94±0.88)% vs(0.89 ±0.21)%, t=2.152, P=0.04]. Plasma ICOSL concentrations in patients with active SLE were significantly higher than those of patients with inactive SLE [(362±25) ng/ml vs (278±15) ng/ml, t=2.356, P=0.025]. We also found a significant negative correlation between the soluble ICOSL expression and the surface ICOSL expression on both mononuclear cells and B cells (r=-0.4243, P=0.022; r=-0.4099, P=0.025). MMPI induced an evident reduction in sICOSL levels released from the cells, which was statistically significant in comparison with untreated cells(P<0.05). Conclusion The up-regulated expressions of ICOS and ICOSL on peripheral lymphocytes and the high levels of plasma concentration of soluble ICOSL are closely correlated with the severity of the disease, suggesting that ICOS/ICOSL pathway may play a critical role in the pathogenesis of SLE. Key words: Systemic lupus erythematosus; Costimulatory molecules; Inducible co-stimulator; Inducible co-stimulator ligand