系统性红斑狼疮患者B细胞激活后FcγRⅡb1向脂筏信号域转移减少

Decreased FcγRⅡb1 translocation to lipid raft signaling domains in activated B lymphocytes from patients with systemic lupus erythematosus

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 in FcyR H bl translocation to lipid raft signaling domains in activated B lymphocytes from patients with systemic lupus erythematosus （SLE）. Methods The peripheral blood of SLE patients and healthy subjects were collected, and B lymphocytes were isolated. The cells were stimulated with F（ab＇）2 fragments of anti-p chain antibodies [ F（ab＇） 2 anti-p, for B cell receptor （BCR） crosslinking ] or with whole immunoglobulin G （IgG） anti-μ chain antibodies （IgG anti-p, for BCR and FcyR g bl co-crosslinking）. The lipid rafts in the cell membrane were extracted by density-gradient ultracentrifugation. FcγRⅡb1 localization, FcyR IT bl tyrosine residue phosphorylation, and SH2-containing inositol phosphatase （SHIP） recruitment to FcγRⅡb1 in the lipid rafts were detected by immunoprecipitation and Western blotting. Results After B lymphocyte stimulation with F （ab＇）2 anti-μ,FcγRⅡb1 translocation to lipid rafts, as well as tyrosine-phosphorylated FcyRIIbl and SHIP recruitment to FcγRⅡb1 in the lipid rafts, showed no significant changes in the B lymphocytes from SLE patients compared with those in the healthy control subjects. However, after B lymphocyte stimulation with IgG anti-μ, the above indexes were significantly lower in the B lymphocytes from SLE patients than in the healthy control subjects. Conclusion This study provides evidence for the decreased FcyR g bl translocation to lipid rafts as well as for the reduced tyrosine-phosphorylated FcγRⅡb1 and SHIP recruitment to FcyR g bl in lipid rafts of B lymphocytes from SLE patients after stimulated with IgG anti-μ.