Antiendomysial antibodies in Berger's disease

The finding of increased levels of immunoglobulin A (IgA) against food antigens in patients with IgA nephropathy prompted the hypothesis of an association between IgA nephropathy and celiac disease (CD). Attention was initially directed to antigliadin antibodies, then to IgA antiendomysial antibodies (IgA-EMA). IgG1-EMA have been found in patients with CD with IgA-EMA-negative results. The presence of IgA- and IgG1-EMA was investigated in 36 patients with IgA nephropathy, 15 patients with other primary glomerulonephritis, and 15 patients with lupus nephritis. IgA-EMA and IgG1-EMA were detected by indirect immunofluorescence analysis. At the time of renal biopsy, the following factors were evaluated: history of macroscopic hematuria, serum creatinine level, urinalysis, 24-hour proteinuria, blood pressure, and histological classification of IgA nephropathy. Sixteen of 36 patients with IgA nephropathy (44.4%) showed EMA positivity. Among patients with positive EMA, 12 patients (75%) were IgG1-EMA positive, 2 patients (12.5%) were IgA-EMA positive, and 2 patients (12.5%) were positive for both isotypes. No significant differences were observed between the two groups (EMA positive versus EMA negative) concerning age, serum creatinine level, macroscopic hematuria, blood pressure, 24-hour proteinuria, or degree of renal histological involvement. IgA- and IgG1-EMA were not detected in patients with other primary nephropathies or lupus nephritis. These results, based on the finding of IgG1-EMA, suggest a common pathogenetic pathway for CD and IgA nephropathy. On this basis, the presence of IgG1-EMA and/or IgA-EMA should be investigated in patients with IgA nephropathy. Furthermore, the role of a gluten-free diet in the natural history of IgA nephropathy, at least in EMA-positive patients, needs to be ascertained.