Abstract: Objective To investigate the expression of inducible co-stimulator (ICOS) on T lymphocytes in peripheral blood from the patients with systemic lupus erythematosus (SLE). Methods Two-color immunofluorescent staining and flow cytometric assay were used to analyze the level of ICOS expression on T lymphocytes in peripheral blood from 33 SLE patients and 16 healthy volunteers. The data of systemic lupus erythematosus diseases activity index (SLEDAI) in SLE patients were also collected. Results The level of ICOS expression on T cells from active SLE group was markedly higher than that in the control group and the inactive SLE group (P<0.01). But there was no significant difference between the inactive SLE group and the control group (P>0.05). However, a positive correlation between the expression level of ICOS and the SLEDAI score was found in both active SLE group and inactive SLE group(r=0.711,P=0.001、r=0.561,P=0.03). Conclusions The expression of ICOS on T cell in peripheral blood from active SLE is increased, which might play a role in the pathogenesis of SLE.

Key words: Lupus erythematosus, systemic, Molecule, inducible co-stimulatory, T-lymphocytes, Antigens, CD28