SELECTIVE BINDING OF IGG4 AND OTHER NEGATIVELY CHARGED PLASMA-PROTEINS IN NORMAL AND DIABETIC HUMAN KIDNEYS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 115  (3) , 443-446
Abstract
Renal tissue from 9 patients with diabetes mellitus (4 with mild and 5 with end-stage disease) and 3 with antiglomerular basement membrane (GBM) nephritis, as well as 5 normal human kidneys, were examined by immunofluoresence microscopy for the presence of plasma proteins of varying isoelectric point (pI). In normal and diabetic kidneys, IgG deposition in basement membranes was restricted to IgG4 (PI 5.5-6.0), the subclass present in lowest concentration in human plasma. IgG1, IgG2 and IgG3 (pI 7.0-9.5) were not detected. In anti-GBM nephritis, all 4 subclasses were present in a linear pattern in GBM. Other plasma proteins of low isoelectric point were detected in basement membranes: albumin (pI 4.9), .alpha.-1-acid glycoprotein (pI 2.7), amyloid P (pI 3.9-4.8) and .alpha.-1-antitrypsin (PI 4.5). The hypothesis that circulating anionic plasma proteins are electrostatically bound in vivo to positively charged moieties in normal and especially diabetic basement membranes is evidently supported.