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, 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 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.