A．黏膜免疫与IgA肾病发病机制无关
B．IgA肾病患者血清中IgAl较正常人显著增高
C．IgA肾病患者血清中IgAl的糖基化缺乏
D．在肾小球系膜区沉积的：IgA免疫复合物几乎为IgAl
E．IgA肾病患者血清中IgAl较正常人显著降低