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Immune deposit glomerulonephritis has been associated with hepatitis B antigenemia. Immune complexes of this antigen and its antibody have been implicated in the pathogenesis of the renal disease. A boy had acute immune complex disease with glomerulitis in which cryoprecipitable complexes of HbsAg and its antibody were isolated from serum. HbsAg was concentrated in the cryoprecipitate and localized in a granular pattern along the glomerular basement membrane in association with immunoglobulins. Glomerular fixed antibody was eluted and shown to be directed against HbsAg. The level of antibody activity to HbsAg was higher in the eluate than the serum, suggesting immunopathogenic specificity of the antibody. The study demonstrates that the nephritis was mediated by immune complexes of HbsAg and its antibody, and the presence of immunoglobulin on the kidney did not represent trapping from the circulation.

The sequence of events in the relationship between membranous nephropathy and renal vein thrombosis is controversial. We postulate that occasionally, the thrombosis may precede the nephropathy and that release of autologous antigens from renal tissue damaged by occlusion of the vein may incite an autologous immune-complex disease. In a case of membranous nephropathy associated with renal vein thrombosis, renal tubular epithelial antigen (RTE) was localized in the glomerulus, along with the host immunoglobulins and complement components. Cryoproteins isolated from the serum contained RTE and anti-RTE. In addition, immunoglobulin eluted from the diseased glomeruli showed antibody activity to RTE. The membranous nephropathy was demonstrated to be secondary to an autologous immune-complex nephritis. Although the sequence of events is inconclusive, it is possible that the renal vein thrombosis preceded and was involved in the etiopathogenesis of the autologous immune-deposit nephropathy.

A variety of renal structural and functional abnormalities have been associated with sickle cell disease. To define the relationship between the hemoglobinopathy and glomerular disease, clinicopathologic correlations, renal morphologic, ultrastructural immunohistologic and functional studies were performed on seven patients with clinical and laboratory evidence of glomerular disease. In addition, immunologic studies including isolation and characterization of cryoprecipitable immune complexes, and determination of immunoglobulin, total complement and complement component levels, and antibody titers to several antigens were performed in an attempt to define the etiologic and pathogenic mechanisms of the renal disease and its relationship to sickle cell anemia. Proteinuria was presnet in all patients. The nephrotic syndrome, hypertension, hematuria and renal insufficiency were found in more than one half the patients. All patients had membranoproliferative glomerulonephritis of varying degree; glomerular basement membrane splitting, electron dense deposits in the glomerulus; interstitial fibrosis, tubular atrophy and hemosiderin deposits were frequent. Immunoglobulin complement components (classif complement pathway) and renal tubular epithelial antigen were distributed in a granular pattern along the glomerular basement membranes of all patients studied by these methods. Cyroprecipitable complexes of renal tubular epithelial antigen-antibody to renal tubular epithelial antigen as well as antibody to renal epithelial antigen were detected in the circulation of some patients. There was no serologic evidence of activation of the alternate complement pathway. These studies demonstrated an immune deposit normocomplementemic nephritis associated with sickle cell anemia; they further support our hypothesis that the relationship is more then coincidental, and is mediated by glomerular deposition of immune complexes of renal tubular epithelial antigen-antibody to renal tubular epithelial antigen, the antigen possibly released after tubular damage secondary to oxygenation and hemodynamic alterations related to sickle cell disease.

Immune deposit renal disease followed intravenous or intraperitoneal injections of neuraminidase treated homologous IgG or neuraminidase alone. No alterations were associated with several groups of controls. This preliminary study suggests that one mechanism by which microogranisms may be involved in the development of immune renal disease is by chemical alteration of immunoglobulin.

Acute glomerulonephritis developed in a man with pneumococcal pneumonia. Serum complement studies revealed decreased levels of C4, properdin, and C3. Renal immunofluorescence studies demonstrated pneumococcal antigen, C1q, C4, C3 proactivator, properdin, C3, IgG, and IgM. Circulating cryoglobulin contained pneumococcal antigen and antibody, C3, and immunoglobulins. Serial pneumococcal antigen and antibody levels did not display patterns that were characteristic of classical immune elimination, but the patterns may have been influenced by the reentry of antigen. A diffuse, pulmonary alveolitis also developed in the patient. Lung immunofluorescence studies revealed pneumococcal antigen, IgG, and C3 in alveolar walls and capillary basement membranes. The glomerulonephritis and alveolitis resolved after a prolonged course. These findings provide presumptive evidence for pneumococcal, immune complex glomerulonephritis with complement activation via both classical and alternative pathways and suggest an immunologic pathogenesis for the pulmonary alveolitis.

A renal tubular epithelial antigen (RTE)--anti-RTE autologous immune complex nephritis associated with sickle cell anaemia (SS) has been reported, but immune complex nephritis has never been described in patients with sickle cell trait (SA). During investigation of a child with "asymptomatic proteinuria" cryoprecipitable complexes of RTE-anti-RTE were detected in the serum and granular deposits of RTE, immunoglobulins, and complement localised on the glomerular basement membranes. Morphological and ultrastructural studies showed increased mesangial matrix, sickled red blood cells in the glomeruli and vessels, and tubular and interstitial abnormalities. These findings prompted haemoglobin electrophoretic studies, which showed previously undiagnosed haemoglobin SA in this patient and her family. These observations suggest that nephritis mediated by similar immunopathogenic mechanisms may be associated with SS and SA haemoglobinopathy. Under some conditions patients with sickle cell trait may experience haemodynamic and oxygenation abnormalities, which may be aetiological factors in the immune complex nephritis associated with SS disease.