Serial samples from 40 patients with acute poststreptococcal glomerulonephritis (AGN) were studied. Early in the disease, all patients showed decreased C3, and C5 and/or properdin values were low in 91%. The concentrations of C1q, C1s, C2, C4 and factor B were largely normal or increased. Concluding from determinations of C-reactive protein, orosomucoid and α1-antitrypsin, complement component levels were influenced by an acute-phase reaction related to infection preceding AGN. Increased amounts in serum of α2-complexes composed of C1r, C1s and C1 inactivator proteins in 83% and moderately reduced C2 in 23% of the patients gave evidence of classical pathway activation during the early phase of AGN. Early in the disease, C3-cleaving activity in serum was found in 72%. The activity was heat-labile and produced C3 cleavage in serum chelated with Mg++ EGTA and in some cases also in the presence of EDTA. The findings suggested that complement activation early in AGN proceeds mainly by an alternative pathway mechanism. In 2 patients, activation of the classical pathway occurred fairly late in the disease and was then associated with the transient appearance of heat-stable C3-cleaving activity in serum. Serial measurements of C1q-binding substances were not clearly informative as to the role of circulating immune complexes in AGN.
No takes yet. Share an insight, caveat, or question.
Anders G. Sjöholm (2009) studied this question.