负性协同刺激分子PD-1在重症肌无力患者外周血中的表达

目的 观察重症肌无力(MG)患者外周血中负性协同刺激分子programmed death-1( PD-1)的表达情况，并探讨其与MG发病的关系。方法 采用免疫荧光标记、流式细胞仪检测45例MG患者和33名健康对照者外周血单个核细胞中PD-1及其配体PD-L1的表达，用ELISA法检测各组血浆中可溶性PD-1的水平。结果 (1)MG患者表达PD-1的CD4+T淋巴细胞比例增加，CD14+PD-L1+的单核细胞比例增加，但在不同性别及眼肌型与全身型间差异无统计学意义；在胸腺异常MG患者中CD4+PD-1+T细胞增加，CD14+ PD-L1+的单核细胞比例减少；早发型MG患者（年龄＜40岁）CD4+PD-1+T淋巴细胞比例明显低于晚发型（年龄≥40岁）。(2)MG患者血浆中sPD-1浓度为(6.92 +0.72) ng/ml，明显高于健康对照组的(3.28±0.42) ng/ml，但在性别、MG眼肌型与全身型不同类型间和有无胸腺异常各组间差异无统计学意义，且sPD-1与发病年龄呈负相关(r=-0.526，P=0.000)。结论 PD-1及PD-L1途径参与了MG的发病，异常升高的sPD-1可能干扰了正常的细胞膜上PD-1与PD-L1的结合，从而促使疾病进展。

Expression of programmed death-1 in peripheral blood of myasthenia gravis patients

Objective To explore the relationship between the negative co-inhibitor programmed death-1 ( PD-1 ) and the pathogenesis of myasthenia gravis ( MG), by detecting the expression of PD-1 and programmed death ligand-1 ( PD-L1 ) on peripheral blood mononuclear cells (PBMCs) and soluble PD-1 (sPD-1) in plasma from myasthenia gravis patients. Methods Peripheral blood samples were collected from 45 MG patients and 33 healthy persons without prednisone or other immunodepressant treatment during the half year ahead of withdrawal. The expression of PD-1 and PD-L1 on PBMCs were detected using immuno-fluorescence labeling and flow cytometry, and the concentrations of sPD-1 in plasma were measured using an ELISA kit. Results(1) The proportion of CD4+ PD-1 + T cells, as well as CD14+ PD-L1 +monocytes of the MG group was higher than that of the control group. There were no significant differences in the proportion of CD4+ PD-1 + T cells or CD14+ PD-L1 + monocytes in the MG sub-groups between different genders or MG types. While the proportion of CD4+ PD-1 + T cells of the late-onset MG (age ≥40) group was higher than that of the early-onset MG group (age ＜40). And it was higher in the MG patients with thymoma or thymus hyperplasia than that from the MG patients with normal thymus. The proportion of CD14+ PD-L1 +monocytes from the MG patients with thymoma or thymus hyperplasia group decreased obviously compared with that of the patients with normal thymus group; but no difference could be found between the late-onset group and early-onset group. (2)The concentration of sPD-1 in the plasma from the group of MG patients was(6. 92 ±0. 72) ng/ml,which was higher than that of the healthy control group ( (3.28 ±0. 42) ng/ml),even more, it was significantly higher in the early-onset MG group than that of the late-onset MG group,there was a negative correlation( r =-0. 526, P =0. 000) between the age of onset and the concentration of sPD-1. Conclusions The increased expressions of PD-1 on CD4+ T cells and PD-L1 on CD14+ monocytes in MG patients suggested the involvement of the couple of molecules in the pathogenesis of MG. Higher concentration of soluble PD-1 in the plasma of patients with MG suggested that it might disturb the ligation of PD-1 and PD-L1 on T cells and antigen presenting cells, which might result in the abnormal transportation of the negative modulating signal, and accelerate the pathological progress of MG.