[Immunopathological study in membranoproliferative glomerulonephritis].

In 39 renal percutaneous biopsies, practiced to 31 patients with membranoproliferative glomerulonephritis (GMP) with subendothelial deposits (DSE), a study with immunofluorescence technique and light microscopy was carried out. In all cases, heavy granular deposits of C3 were detected in the loops of the glomerular capillaries and in a variable proportion of cases, deposits of IgM, IgA, C3PA (factor B) and C1q of similar aspect and localizacion were found. These findings suggest immunologic pathogenesis. In the absence of C1q, no cases with factor B were found; thus, it is possible to assert that the activation of the complement system takes place exclusively through an alternate pathway, as was previously accepted. On the other hand, it was found that the presence of C1q was correlated with a faster evolution to chronic renal failure and with the presence of a higher percentage of glomeruli with extracapillary proliferation (crescents). Thus, it is concluded that activation of C1q in patients with MPG and SED, may play a role in formation of crescent and consequently, it is a sign of poor prognosis.