Study of Haemophilus parainfluenzae antigen and antibody in the etiology of IgA nephropathy

我们以前证明了副流感嗜血杆菌（HP）抗原（OMHP）和伊加肾病的外膜之间的密切关系。目的：用酶联免疫吸附试验（ELISA）检测44例伊加肾病和62例其他肾小球疾病（OGD）患者血清中抗OMHP IgA、IgG和IgM类抗体（Ab），探讨三者之间的关系。伊加肾病患者血清中抗OMHP的IgA-Ab（P<0.0005）和IgG-Ab（P<0.001）均显著高于OGD患者，伊加肾病患者血清中抗OMHP的IgA-Ab与IgG-Ab、IgA-Ab与IgM-Ab、IgG-Ab与IgM-Ab呈正相关。免疫印迹显示，IgA肾病患者血清中抗OMHP的伊加-、IgG-或IgM-Ab均与OMHP的组分结合，IgA肾病患者血清识别的OMHP的三种组分的氨基酸序列与已报道的外膜蛋白P6前体、OMP P5、OMP P6前体、OMP P5前体、OMP P6前体、OMP P5前体结果提示，伊加肾病患者肾小球内存在HP的OMP P6前体、OMP P5或P2孔蛋白沉积，以及通过针对OMHP的多克隆活化而特异性增加针对OMHP的IgA-Ab的产生，其中产生从一种同种型转换为另一种同种型，例如从IgM转换为伊加。

We previously demonstrated a close relationship between the outer membranes of Haemophilus parainfluenzae (HP) antigens (OMHP) and IgA nephropathy. Our objective was to clarify the relationship among IgA-, IgG-, and IgM-class antibody (Ab) against OMHP in the sera of 44 patients with IgA nephropathy and 62 patients with other glomerular diseases (OGD) by enzyme-linked immunosorbent assay (ELISA). Patients with IgA nephropathy showed a significantly higher level of IgA-Ab (P<0.0005) and IgG-Ab (P<0.001) against OMHP,than did patients with OGD.Positive correlations were observed between IgA-and IgG-Ab, between IgA-and IgM-Ab, and between IgG-and IgM-Ab against OMHP in the sera of patients with IgA nephropathy. Immunoblotting showed that IgA-, IgG-, or IgM-Ab against OMHP in the sere of all patients with IgA nephropathy bound to the components of OMHP.Amino acid sequences of three components of OMHP recognized by the sera from patients with IgA nephropathy revealed the homology with those reported for outer membrane protein (OMP) P6 precursor, OMP P5, and P2 porin protein of Haemophilus influenzae.Results suggest that patients with IgA nephropathy have glomerular deposits of OMP P6 precursor, OMP P5, or P2 porin protein of HP,and a specific increase in the production of IgA-Ab against OMHP via polyclonal activation against these, with switching of production from one isotype to another, eg, from IgM to IgA.