Increased expression of human T-cell immunoglobulin-and mucin-domain-containing molecule-4 in peripheral blood mononuclear cells from patients with system lupus erythematosus

Systemic lupus erythematosus （SLE） is a prototypic autoimmune disease. Innate and adaptive immunity cooperatively contribute to the development of SLE. Antigen-presenting cells （APCs） have been suggested to link innate and adaptive immunity. T-cell immunoglobulin- and mucin-domain-containing molecule-4 （Tim-4; also known as Timd4）, expressed primarily on the surface of APCs, is a member of the TIM family, a recently described group of molecules that have received much attention as potential regulators of the immune system. In this study, we used quantitative real-time reverse transcription-polymerase chain reaction to examine the mRNA expression of Tim-4 in peripheral blood mononuclear cells （PBMCs） from SLE patients and further analyzed the correlation between the expression of Tim-4 and Tim- 1 （a potential l igand for Tim-4） in PB MCs and serum tumor necrosis factor （TNF）-a levels. The results showed that Tim-4 mRNA expression in PBMCs was significantly higher in SLE patients than in healthy controls, especially those patients in the active phase of disease. Moreover, Tim-4 mRNA levels were closely correlated with Tim- 1 mRNA levels in PBMCs and with serum TNF-a levels in SLE patients but not in the control group. Taken together, these results demonstrate that Tim-4 may be involved in the pathogenesis of SLE.