Immunoglobulin A (IgA) associated glomerulonephritis

Immunoglobulin A (IgA) associated glomerulonephritis. Adequate tissue from 153 glomerulonephritic patients was examined by direct immunofluorescence for glomerular-bound immunoglobulins, β1C, and fibrinogen. Ninety-six specimens contained immunoglobulins; 15 (16%) that contained significant amounts of IgA were from patients without systemic lupus erythematosus or other identifiable systemic disease. IgA, usually visualized in association with other immunoglobulins, was the most plentiful; in three biopsies it was the only immunoglobulin. IgA deposition was primarily mesangial, and to a lesser degree along peripheral glomerular capillary loops; electron-dense deposits and cellular proliferation also were principally mesangial in location. All patients had persistent microhematuria, while seven had at least one episode of gross hematuria; renal failure occurred in two patients and nephrotic syndrome in one of them. No clinical event was related to the onset of renal disease in these patients. Although three had low circulating levels of β1C, and three sera were positive for rheumatoid factor, none had cryoglobulins, antinuclear antibodies or abnormal immunoglobulin concentrations. Sera tested by hemagglutination for antiIgA antibodies and biopsies tested for antiIgG antibodies were negative. Eluates from three needle biopsies failed to bind to normal human kidney sections in vitro; an eluate from a nephrectomy organ contained IgA which fixed weakly to non-basement membrane intraglomerular components. Glomérulonéphrite associée à l'immunoglobuline A (IgA). Du tissu rénal de 153 malades atteints de glomérulonéphrite a été examiné en immunofluorescence pour détecter les immunoglobulines le β1C et le fibrinogène déposés sur le glomérule. Quatre vingt seize échantillons contenaient des immunoglobulines; 15 (16%) qui contenaient des quantités importantes d'IgA provenaient de malades atteints de lupus érythémateux disséminé ou d'autres maladies de système identifiables. L'IgA, habituellement associée à d'autres immunoglobulines, était la plus abondante. Dans trois biopsies elle était la seule immunoglobuline. Les dépôts d'IgA étaient principalement mésangiaux et, à un moindre degré, le long des anses capillaires périphériques. Des dépôts denses en microscopie électronique et une prolifération cellulaire étaient aussi principalement mésangiaux. Tous les malades avaient une hématurie microscopique persistante, sept d'entre eux eurent au moins une hématurie macroscopi