BACKGROUND C5a is important for antineutrophil cytoplasmic antibody (ANCA)-mediated activation of neutrophils. The present study aimed to assess the role of macrophage migration inhibitory factor (MIF) in ANCA-mediated activation of C5a-primed neutrophils. The effects of MIF on ANCA-mediated neutrophil respiratory burst and degranulation were determined. In addition, the effect of a MIF antagonist on the activation of C5a-primed neutrophils was assessed. RESULTS MIF treatment resulted in increased membrane proteinase-3 (mPR3) expression on neutrophils and enhanced myeloperoxidase (MPO) amounts in neutrophil culture supernatants. The concentration of MIF was significantly higher in the neutrophils supernatant primed with C5a (negative control: 14.2 ± 1.16 ng/ml; C5a: 45.8 ± 2.8 ng/ml, P < 0.001 vs. negative control; C5a + IgG: 44.8 ± 1.93 ng/ml, P < 0.001 vs. negative control; C5a + MPO-ANCA: 73.0 ± 5.5 ng/ml, P < 0.001 vs. C5a; and C5a + PR3-ANCA: 69.4 ± 5.35 ng/ml, P < 0.001 vs. C5a). MIF primed neutrophils to undergo respiratory burst and degranulation in response to ANCA. Indeed, mean fluorescence intensity (a measure of respiratory burst) was significantly higher in MIF-primed neutrophils activated with MPO-ANCA-positive IgG or PR3-ANCA-positive IgG compared with non-primed neutrophils. Meanwhile, a MIF antagonist reduced oxygen radical production in C5a-primed neutrophils treated with patient-derived ANCA-positive IgG. CONCLUSIONS MIF can prime neutrophils to undergo ANCA-mediated respiratory burst and degranulation. Blocking MIF resulted in reduced ANCA-mediated activation of C5a-primed neutrophils. These findings indicated that the interaction between MIF and C5a may contribute to ANCA-mediated neutrophil activation.

中文翻译：

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巨噬细胞迁移抑制因子参与抗中性粒细胞胞浆抗体介导的C5a引发的中性粒细胞的活化。

背景技术C5a对于抗中性粒细胞胞浆抗体（ANCA）介导的中性粒细胞活化很重要。本研究旨在评估巨噬细胞迁移抑制因子（MIF）在ANCA介导的C5a引发的中性粒细胞活化中的作用。确定了MIF对ANCA介导的中性粒细胞呼吸爆发和脱粒的影响。另外，评估了MIF拮抗剂对C5a引发的中性粒细胞活化的作用。结果MIF处理导致嗜中性粒细胞膜蛋白酶3（mPR3）表达增加，嗜中性粒细胞培养上清液中的髓过氧化物酶（MPO）量增加。用C5a灌注的中性粒细胞上清液中MIF的浓度明显更高（阴性对照：14.2±1.16 ng / ml; C5a：45.8±2.8 ng / ml，与阴性对照相比，P <0.001; C5a + IgG：44.8±1.93 ng / ml，与阴性对照相比，P <0.001；C5a + MPO-ANCA：73.0±5.5 ng / ml，相对于C5a，P <0.001；C5a + PR3-ANCA：69.4±5.35 ng / ml，相对于C5a，P <0.001）。MIF引发中性粒细胞响应ANCA发生呼吸爆发和脱粒。实际上，与未引发中性粒细胞相比，被MPO-ANCA阳性IgG或PR3-ANCA阳性IgG激活的MIF引发中性粒细胞的平均荧光强度（呼吸猝灭的量度）明显更高。同时，MIF拮抗剂减少了用源自患者的ANCA阳性IgG治疗的C5a引发的中性粒细胞的氧自由基产生。结论MIF可以引发中性粒细胞发生ANCA介导的呼吸爆发和脱粒。阻断MIF导致减少的ANCA介导的C5a引发的中性粒细胞活化。