Clinicl Significance of Mesangial IgM Deposits in Minimal Change Nephrotic Syndrome

The clinicopathologic features and the response to corticosteroid therapy were compared in 9 patients with minimal change nephrotic syndrome (MCNS) and diffuse mesangial IgM deposits (Group I) and in 32 of those without IgM deposits (Group II). However, serum IgM levels in Group I in both relapse and remission were significantly higher than those of Group II and controls (p<0.001). In Group I mesangial IgM deposits were diffuse in 9 (100%), mesangial C_1q was present in 4, IgA and fibrinogen were each observed in 1, respectively. Electron dense deposits in the mesangium were also present in 2 to 5 patients in Group I. No significant differences were found between the two groups in age of onset, sex ratio, laboratory data except for serum IgM level, duration before biopsy, follow-up periods, outcome, and response to steroid therapy. Our data suggest that a more severe degree of either impairment of mesangial clearance of IgM or overproduction of IgM may be involved in patients with MCNS and mesangial IgM deposits but that these patients could not be considered a distinct group of patients.