Clinical and immunopathologic study of mesangial IgM nephropathy: report of 41 cases

Abstract

Forty-one out of 408 cases (or 10%) of primary glomerular disease had diffuse fine granular to arc-like short linear mesangial deposits of IgM by direct immunofluorescence. The IgM deposition was accompanied by C1q and/or C4 in the same locality in 29 cases, by C3 in 10, and by trace amounts of IgA in 6. Properdin-factor B was not detected. Fine granular electron dense deposits of low density were detected in the mesangium in all 41 cases by electron microscopy, usually as a discrete granular or arc-like pattern beneath the mesangial glomerular basement membrane and correlated well with the immunofluorescence findings. An immune complex disease with complement activation via the classical pathway is suggested. The ages of the patients varied from 2 to 58 years (average 23.8 years). A male predominance of 2.2:1 was identified. Serum IgM level was elevated in 46.7% of the cases. The majority (87.8%) of the cases manifested a nephrotic syndrome or relapse at time of biopsy, and the remaining cases experienced persistent or intermittent proteinuria. Among the 36 nephrotic patients, 22 cases (61.1%) demonstrated complete remission with steroid therapy, 9 cases (25%) were resistant, and 5 cases (13.9%) had partial remission. Complete and partial remissions were later achieved with cytotoxic drugs or methylprednisolone pulse therapy in 3 and 4 cases respectively in the steroid resistant patients. Frequent relapses occurred during the course in 22 out of 32 cases (68.8%) who had experienced complete or partial remission. Follow-up study after biopsy demonstrated that sustained complete remission was achieved with prednisolone with or without cytotoxic drugs and pulse therapy in only 14 (42.4%) of the 33 nephrotic cases who had been followed up for longer than 6 months, and six of them had had previous relapses. Pathologically, 56.1% of the patients showed mild to moderate increase in mesangial matrix and cellularity. Focal and segmental sclerosis was demonstrated in four cases (9.8%). However, minimal glomerular change was also common (34.1%). The patients with minimal change seemed to have a higher complete remission rate than patients with more evident glomerular alterations, although the difference was not statistically significant. This clinical and immunopathological study suggests that mesangial IgM nephropathy is an important disease in Taiwan, with a variable response to treatment and frequent relapses.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical Significance of IgM and C3 Glomerular Deposition in Primary Focal Segmental Glomerulosclerosis

“…We found that the patients with IgM deposition presented with higher levels of serum IgM. This is consistent with the observations in IgM nephrology (23,24). These data implied that the glomerular IgM deposits are composed of specific clones of IgM, possibly from B-1a B cells (3,25,26), which are produced in circulation and bind to some epitopes on sclerotic segments.…”

“…The pathologic variants and percentage of sclerotic glomeruli were also comparable between the two groups. These findings indicated that IgM deposition is not likely the initiation of FSGS lesion, which has been identified as several genes mutations or variants (9-13), circulating permeability factors (14)(15)(16), and others (17)(18)(19)(20)(21)(22)(23). However, IgM and complement-mediated injury may be secondary phenomena that occur after the primary renal insult.…”

IgM Contributes to Glomerular Injury in FSGS

“…6 Importantly, C3 and C4 are frequently detected in the glomeruli of patients who have IgM deposits. 4,7,8 In spite of its promiscuous presence in glomerular lesions, a pathogenic role for glomerular IgM has not been demonstrated. Some series, however, have shown that the presence of IgM is of prognostic significance.…”

Impact of Immunofluorescence on the Histological Pattern of Pediatric Kidney Biopsies from Northern Pakistan

“…However, many of us regard it as a distinct histological entity with different response to steroid, requiring immunosuppressant therapy. [6][7][8][9][10][11] We believe that IgM nephropathy remains a separate histological entity with steroid responsiveness, course, and prognosis far different from MCD. About 23.5% of our cases showed renal insufficiency with a serum creatinine varying from 1.4 to 5 mg%.…”