Uptake of aggregated immunoglobulin by the mouse kidney. II. Effect of hydrocortisone

The uptake of radiolabelled (125I) aggregated human IgG (AggIgG) by the renal cortex, liver, spleen and lung was evaluated quantitatively in mice treated with hydrocortisone (HC) (25 mg) 72 h previously. AggIgG was administered in a dose of 1.5 or 3.5 mg/g body wt i.v.; tissue and blood were obtained at 1, 4 and 24 h. Renal cortical and mesangial uptake of AggIgG was significantly increased in HC animals. A rise in blood level was also observed in association with decreased splenic uptake, normal or slightly increased hepatic uptake and unchanged lung uptake. A significant increase in the kidney:lung and kidney:spleen ratios of AggIgG was induced by hydrocortisone, suggesting a relatively greater rate of loss from the spleen and liver than the renal cortex. The increased mesangial uptake may be a consequence of higher blood levels of AggIgG, as well as a direct effect of HC on the mesangium.