| T cell immunoglobulin mucin-3 (Tim-3) was originally described as a Th1-specific surface marker. But since then its mRNA has been detected in many cell types of both mice and human. Tim-3 expression increases during T cell activation, and suppresses the ability of T cells to secrete cytokines and proliferate. Many studies have demonstrated that Tim-3 participates in the pathogenesis of autoimmune diseases. But most of these discoveries came from animal studies, and by detecting Tim-3 transcript. In our previous study, increased Tim-3 mRNA in CD4~+ T cells was found in rheumatoid arthritis(RA). Our research project proceed further to examine Tim-3 expression at protein level on different subsets surface of both human peripheral blood mononuclear cells(PBMC), and CD4~+ T cells from RA patients.Objective:To observe Tim-3 expression on different subsets of human PBMC and activated CD4+ T cells. To observe changes of Tim-3 expression on different subsets of RA patients'CD4~+ T cells, and investigate the correlation of Tim-3 expression with functions of CD4~+ T cells, and the its role in the pathogenesis of RA.Methods:Tim-3 expression was detected by FACS on CD4~+ T cells, CD8~+ T cells, CD19~+ B cells, CD14+ monocytes, CD3- CD56+ NK cells of fresh peripheral blood from 6 healthy volunteers.CD4~+ T cells of fresh peripheral blood from 7 healthy volunteers and 7 RA patients, purified by MACS, were cultured in vitro and stimulated with PMA and Ionomycin. After 48h, expressions of Tim-3, IFN-γ, and IL-4 were detected by FACS.Results:1. Tim-3 expression on human PBMCA. Tim-3~+ cells in human peripheral blood lymphocytes were mainly NK cells, followed by CD8+ T cells and CD4+ T cells.B. The percentage of Tim-3~+ cells in monocytes was higher than other detected subsets, including CD4+ T cells, CD8+ T cells, NK cells and B cells (21.51%±7.99% vs 1.03%±0. 54%, 1.58%±0. 47%, 11.00%±4.10 %, 7.93%±8.76%, P <0.05).2. Tim-3 expression on human peripheral blood CD4+ T cellsA. Increased percentage of Tim-3~+ cell was present in CD4+ T cells after activated by non-specific stimulation (2.27%±0.62% vs 1.03%±0.54%, P <0.05).B. Only 17.34%±9.06% Tim-3~+ cells in human peripheral blood CD4+ T cells were Th1 cells, and 1.26%±2.18% were Th2 cells, suggesting that some undetected subsets of CD4+ T cells may also express Tim-3.C. In activated CD4+ T cells, the percentage of Tim-3~+ cell in IFN-γ+ cells was higher than IFN-γ- cells (7.67%±4.63% vs 2.08%±0.69%, P <0.01).3. Changes of Tim-3 expression on CD4+ T cells in RAA. The percentage of Tim-3~+ cell in CD4+ T cells increased in RA compared with controls (5. 34%±3.83% vs 0.62%±0.69%, P <0.01).B. The percentage of Tim-3~+ cell in Th1 cells increased in RA compared with controls (5. 34%±3.83% vs 0.62%±0.69%, P <0.01).C. Decreased Tim-3 expresion on Tim-3~+ IFN-γ- cells was observed in CD4+ T cells from RA patients(1602.71±843.67 vs 3777.14±2399.37, P <0.05). Conclusion:Besides CD4+ T cells, there are subsets of human PBMC expressing Tim-3, including monocytes, NK cells, CD8+ T cells. The percentage of Tim-3~+ cells in monocytes is higher than other detected subsets.There may be some undetected subsets of CD4+ T cells also expressing Tim-3. Tim-3+ cells increase in CD4+ T cells after activated by non-specific stimulation, with the higher percentage of Tim-3~+ cell in IFN-γ+ cells than IFN-γ- cells, suggesting that Tim-3 expression may be associated with functions of CD4+ T cell, particularly with the secretion of IFN-γ.Tim-3~+ cells increase in both CD4+ T cells and Th1 cells in RA, suggesting that increased Tim-3 expression on Th1 cells may play a role in RA. Decreased Tim-3 expression on Tim-3~+ IFN-γ- cells from RA patients suggests that Tim-3 expression on undetected Tim-3~+ CD4+ T cell subsets may be associated with RA. |
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