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目的观察系统性红斑狼疮(SLE)患者B细胞激活后FcγRⅡb1信号分子向脂筏信号域转移的改变。方法收集SLE患者和正常人外周血并分离出B细胞,分别用抗人μ链的F(ab’)2片段[F(ab’)2anti-μ]单独刺激B细胞抗原受体(BCR),或用抗人μ链的完整IgG(IgG anti-μ)激活B细胞、同时实现BCR与FcγRⅡb1的交联;采用密度梯度超速离心法提取B细胞膜脂筏;免疫沉淀及Western blot法分别检测膜脂筏中FcγRⅡb1的分布、脂筏FcγRⅡb1酪氨酸残基磷酸化水平、及脂筏FcγRⅡb1对含SH2结构域的肌醇磷酸酶(SHIP)的招募。结果 SLE患者B细胞经F(ab’)2anti-μ单独刺激BCR后,胞膜脂筏部位FcγRⅡb1的分布、脂筏FcγRⅡb1酪氨酸残基磷酸化水平、以及脂筏FcγRⅡb1对SHIP的招募,与正常对照组比较均无明显改变,但经IgG anti-μ激活B细胞以实现BCR与FcγRⅡb1的交联后,以上指标均显著低于正常对照组。结论 SLE患者B细胞经IgG anti-μ激活后,转移至膜脂筏部位的FcγRⅡb1、脂筏FcγRⅡb1酪氨酸残基磷酸化水平、以及脂筏FcγRⅡb1对SHIP的招募均显著减少。
Objective To observe the changes of the FcγRⅡb1 signal transduction to lipid raft signal transduction domain in patients with systemic lupus erythematosus (SLE). Methods Peripheral blood was collected from patients with SLE and normal controls, and B cells were isolated. B cell antigen (BCR) was stimulated with F (ab ’) 2 fragment [F B cells were activated with intact IgG (anti-μ) of human μ chain and cross-linked by BCR with FcγRⅡb1. Lipid rafts of B cell membrane were extracted by density gradient ultracentrifugation. Immunoprecipitation and Western blot were used to detect membrane lipid The distribution of FcyRIIb1 in rafts, the phosphorylation level of lipid raft FcyRIIb1 tyrosine residues, and the recruitment of SHY domain containing inositol phosphatase (SHIP) by lipid rafts FcyRIIb1. Results The distribution of FcγRⅡb1 in lipid rafts, the phosphorylation level of lipid rafts FcγRⅡb1 tyrosine residues, and the recruitment of SHIP by lipid rafts FcγRⅡb1 were significantly increased in B cells of SLE patients stimulated by F (ab ’) 2anti-μ alone The normal control group showed no significant change, but after B cells were activated by IgG anti-μ to achieve the cross-linking of BCR and FcγRⅡb1, the above indexes were significantly lower than the normal control group. CONCLUSIONS: The phosphorylation of tyrosine residues in FcγRⅡb1, lipid rafts FcγRⅡb1 and the recruitment of SHIP in lipid rafts to FcγRⅡb1 were significantly decreased in BLE of SLE patients after IgG anti-μ activation.