Thorner P S, Baumal R, Eddy A, Marrano P M
Department of Pathology, Hospital for Sick Children, Toronto, Ontario, Canada.
Virchows Arch A Pathol Anat Histopathol. 1990;416(3):205-12. doi: 10.1007/BF01678979.
The NC1 domain of the collagen type IV molecule, the major component of glomerular basement membranes (GBM), consists of dimers and 24 kilodalton (K), 26 K and 28 K monomers in man, and contains the Goodpasture antigen. Serum obtained from patients with Goodpasture's syndrome has been reported not to stain GBM of most male and some female patients with hereditary nephritis (HN) by immunofluorescence (IF) microscopy. In the present study, GBM seen on the renal biopsies of 2 patients (one male and one female) with HN were examined by IF to ascertain whether NC1 monomers were detectable. Three reagents were used: a plasmapheresis fluid (PPF) obtained from a patient who was treated for anti-GBM nephritis (human anti-GBM PPF); a commercial rabbit antibody against human NC1; and a rabbit antibody raised by us against dog NC1, which cross-reacted with human NC1. All 3 reagents detected NC1 determinants in GBM of normal human kidney by IF and reacted with human NC1 by a plate-binding radioimmunoassay (RIA). The human anti-GBM PPF bound to 28 K and 26 K monomer components of NC1 by Western blotting, the rabbit anti-human NC1 antibody bound to 26 K and 24 K monomers, while the rabbit anti-dog NC1 antibody bound only to the 26 K monomer. By IF, the human anti-GBM PPF did not stain GBM of the male patient with HN, but produced segmental staining of GBM (i.e., some GBM stained, while others did not) of the female patient. In contrast, the rabbit anti-NC1 antibodies produced global staining by IF of GBM of both patients. The absence of staining (i.e., global or segmental) seen with the human anti-GBM PPF implied that the 26 K and 28 K monomers of NC1 were either absent from GBM, or were present but altered structurally, leading to a diminution in their immunological reactivity. However, the positive staining observed with the rabbit anti-NC1 antibodies implied that the 26 K monomer was actually present in GBM. Hence, we postulate that the 26 K monomer of NC1 in GBM was structurally altered, and that the 28 K monomer was either absent, or present but altered. These findings suggest that there is an abnormality of more than one monomer of NC1 in GBM of patients with HN.
IV型胶原分子的NC1结构域是肾小球基底膜（GBM）的主要成分，在人类中由二聚体以及24千道尔顿（K）、26K和28K的单体组成，并包含Goodpasture抗原。据报道，从Goodpasture综合征患者获得的血清通过免疫荧光（IF）显微镜检查不能使大多数男性和一些患有遗传性肾炎（HN）的女性患者的GBM染色。在本研究中，通过IF检查了2例（1例男性和1例女性）HN患者肾活检中所见的GBM，以确定是否可检测到NC1单体。使用了三种试剂：从接受抗GBM肾炎治疗的患者获得的血浆置换液（PPF）（人抗GBM PPF）；一种针对人NC1的商业兔抗体；以及我们制备的针对犬NC1且与人NC1交叉反应的兔抗体。所有这三种试剂通过IF在正常人肾GBM中检测到NC1决定簇，并通过平板结合放射免疫测定（RIA）与人NC1发生反应。通过蛋白质印迹法，人抗GBM PPF与NC1的28K和26K单体成分结合，兔抗人NC1抗体与26K和24K单体结合，而兔抗犬NC1抗体仅与26K单体结合。通过IF，人抗GBM PPF未使HN男性患者的GBM染色，但使HN女性患者的GBM产生节段性染色（即一些GBM染色，而另一些未染色）。相比之下，兔抗NC1抗体通过IF使两名患者的GBM产生全层染色。人抗GBM PPF未见染色（即全层或节段性）表明GBM中NC1的26K和28K单体要么不存在，要么存在但结构改变，导致其免疫反应性降低。然而，兔抗NC1抗体观察到阳性染色表明GBM中实际存在26K单体。因此，我们推测GBM中NC1的26K单体结构改变，并且28K单体要么不存在，要么存在但结构改变。这些发现表明，HN患者的GBM中NC1的不止一种单体存在异常。
