Relationship of kidney function to immunopathology in chronic serum sickness of rats

Relationship of kidney function to immunopathology in chronic serum sickness of rats. This study sought to clarify the relationship between kidney function and immunopathology in chronic serum sickness (CSS) of rats. CSS was induced by chronic intravenous immunization with bovine serum albumin. Whole kidney function was studied during the course of CSS by assays of serum and urine. Single nephron function was evaluated by micropuncture techniques. Three categories (mild, moderate, severe) ofkidney disease were identified from the analysis of kidney function in rats with CSS. Those categories represented distinct stages in the natural history of CSS nephritis. The three stages identified by measurements of function corresponded to distinct categories of kidney immunopathology. In rats with mild CSS, immune deposits were limited to the mesangium; histopathology was slight or absent. The only detectable change in protein handling was a small elevation of albumin concentration in tubule fluid. Abnormal proteinuria was a feature of moderate CSS; whole kidney glomerular filtration was not decreased despite evidence of significant immunopathology of glomeruli. Compromise of whole kidney function including decreased sodium excretion was only detected in the severe stage of CSS in association with diffuse proliferative glomerulonephritis. The transitions from mild to moderate and moderate to severe CSS were not gradual but occurred as discrete, sudden events. Relations entre la fonction renale et l'immunopathologie au cours de la maladie serique chronique chez des rats. Cette etude est destinee a clarifier la relation entre la fonction renale et l'immunopathologie au cours de la maladie serique chronique (CSS) chez des rats. CSS etait induite par immunisation chronique intra-veineuse avec de la serum albumine bovine. La fonction renale globale etait etudiee pendant la CSS par des dosages seriques et urinaires. La fonction renale individuelle etait evaluee par des techniques de microponction. Trois categories (benigne, moderee, severe) de maladies renales ont ete identifiees a partir de l'analyse de la fonction renale chez les rats atteints de CSS. Ces categories representaient des stades distincts de l'histoire naturelle de la nephrite de CSS. Les trois stades identifies par les mesures des fonctions correspondaient a des categories distinctes d'immunopathologie renale. Chez les rats atteints de CSS benigne, les depots immuns etaient limites au mesangium; l'histopathologic etait minime ou absente. La seule modification detectable de la conservation des proteines etait une elevation modere de la concentration d'albumine dans le fluide tubulaire. Une proteinurie anormale etait une caracteristique de la CSS moderee; la filtration glomerulaire globale n'etait pas diminuee malgre l'existence d'une immunopathologie significative des glomerules. Une alteration de la fonction renale globale comprenant une diminution de l'excretion sodee etait detectee seulement au stade severe de CSS, en association avec une glomerulonephrite proliferative diffuse. Les passages de la forme benigne a la forme moderee, et de la forme moderee a la forme severe de CSS n'etaient pas progressifs, mais survennaient de facon tranchee, brutale.