Abstract
In an attempt to clarify the participation of immune deposits in progression of glo-merular lesions, relationship between electrondense deposits, especially subepithelial deposits observed by electron microscopy, and light microscopic and clinical findings in 131 patients with IgA nephropathy and 30 with purpura nephritis were studied, Capillary dense deposits together with mesangial deposits were observed in 16 (53%) patients with purpura nephritis in comparison with 46 (35%) with IgA nephropathy, especially subepithelial deposits being more frequently observed in purpura nephritis (15; 50%) than in IgA rephropathy (23; 18%) (p<0.005). In addition, patients with subepithelial dense deposits showed heavier proteinuria with a mean of 1.9+0.2 g/day in IgA nephropathy and of 2.0±0.3 g/day in purpura nephritis, and higher incidence of cellular crescent (9; 39 and 12; 80%, respectively), Furthermore, 5 out of 9 patients with IgA nephropathy, who were in an acute and active phase manifested by an abrupt appearance or increase in urinary protein and gross hematuria, showed subepithelial deposits. In purpura nephritis, 9 of 10 similar patients, all 8 with nephrotic syndrome and 3 with azotemia (Cr>1.5 mg/dl) disclosed subepithelial deposits, Although both daily urinary protein excretion and incidence of cellular crescents were higher in patients with purpura nephritis than those with IgA nephropathy, exacerbations scarcely occurred and prognosis was favourable in the former as compared to the latter, which showed a slowly progressive clinical course. These results suggest that subepithelial deposits develop in the acute and active phase in both diseases but cause different clinical courses as observed in the two diseases, favourable in purpura nephritis and progressive in IgA nephropathy, through difference of duration in disease activity, transient in the former and persistent in the latter.
