Post-streptococcal glomerulonephritis: studies on the interaction between nephritis strain-associated protein (NSAP), complement and the glomerulus

APMIS. 1991 May;99(5):460-6. doi: 10.1111/j.1699-0463.1991.tb05176.x.

Abstract

Nephritis strain-associated protein (NSAP), a streptokinase produced by strains of streptococci isolated from patients with acute glomerulonephritis, is believed to be a specific antigen which participates in the production of glomerular injury. In order to investigate the mechanisms by which NSAP induces damage we have examined its potential to activate complement in vitro and to bind to isolated human glomeruli. NSAP, both alone and in combination with specific antibody, caused depletion of complement in normal human serum as measured by total haemolytic complement activity and generation of the complement breakdown products. C3a and C4a. Furthermore, Scatchard analysis showed that NSAP bound tightly to human glomeruli (Ka of 400 +/- 240 x 10(6) M) when compared to non-nephritic streptokinase (Ka of 7.3 +/- 4.1 x 10(6) M) and fully cationized human serum albumin (Ka of 0.6 +/- 0.04 x 10(6) M). These findings are consistent with the hypothesis that the deposition of streptococcal antigens within the glomerulus may precede the fixation of complement and specific antibody.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism
  • Bacterial Proteins / pharmacology*
  • Blotting, Western
  • Complement System Proteins / drug effects
  • Complement System Proteins / physiology*
  • Glomerulonephritis / etiology
  • Glomerulonephritis / physiopathology*
  • Humans
  • Kidney Glomerulus / drug effects
  • Kidney Glomerulus / physiology*
  • Kinetics
  • Protein Binding
  • Serum Albumin, Bovine / pharmacology
  • Streptococcal Infections / complications*
  • Streptococcus pyogenes / isolation & purification
  • Streptococcus pyogenes / pathogenicity
  • Streptokinase / pharmacology*

Substances

  • Bacterial Proteins
  • nephritis-strain associated protein, group A Streptococcus
  • Serum Albumin, Bovine
  • Complement System Proteins
  • Streptokinase