What is the role of nephritis strain–associated protein (NSAP) in the pathogenesis of acute poststreptococcal glomerulonephritis (APSGN)?

Updated: Dec 05, 2018
  • Author: Rajendra Bhimma, MBChB, MD, PhD, DCH (SA), FCP(Paeds)(SA), MMed(Natal); Chief Editor: Craig B Langman, MD  more...
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NSAP is a 46- to 47-kd protein that is unique to the extracellular products of nephritogenic streptococci. NSAP was demonstrated in glomerular deposits of 14 of 21 patients with APSGN, but none in control biopsy samples from 5 patients with acute kidney injury and 11 with nonstreptococcal glomerulonephritis. NSAP was also detected in serum from 96% of APSGN patients compared with 15-20% of patients with either acute kidney injury or impetigo. [13] NSAP has antigenic, biochemical, and structural similarities to streptokinase from group C streptococcal organisms, binds to plasmin, and is a plasminogen activator. However, streptokinase cannot be demonstrated in glomerular deposits for patients with APSGN, and serum levels of purified group A streptokinase were similar in patients with APSGN and those with acute kidney injury. Thus, although NSAP and streptokinase have similarities, they appear to be 2 distinct proteins. [13]

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