Value of immunofluorescence-mediated detection of Ig, C1q, C3, and FRA for the identification and diagnosis of atypical membranous nephropathy.

OBJECTIVE: The present study was to investigate the value of immunofluorescence- mediated detection of Ig, C1q, C3, and FRA for the identification and diagnosis of atypical membranous nephropathy (AMN). PATIENTS AND METHODS: Fifty-five patients with AMN and 135 patients with idiopathic membranous nephropathy (IMN) diagnosed by renal biopsy in our hospital were consecutively selected. The positive expressions of Ig, C1q, C3, and FRA by immunofluorescence were analyzed. RESULTS: We compared the levels of blood urea nitrogen, creatinine, cystatin C, and 24 h urine protein, and the levels of serum IgA, IgG, IgM, and C3. The differences were not significant (p>0.05). Proportionate increases in glomerular spiky projection formations in patients with AMN were observed by light microscopy, without observation of other pathologic changes. By immunofluorescence, AMN patients showed higher positive rates of deposition of IgA, IgM, C1q, and FRA compared with IMN patients. Comparison of the positive rates of deposition of IgG and C3 showed no differences. By electron microscopy, AMN patients showed higher percentages of mesangial cell and mesangial matrix proliferation. Deposition of electron dense granules was mostly found in subepithelium, inside basement membranes, and in the mesangial area. The comparisons between the two groups showed no differences. CONCLUSIONS: Immunofluorescence-mediated detection of Ig, C1q, C3, and FRA have important application value for the identification and diagnosis of AMN. [ABSTRACT FROM AUTHOR]