Deiodination of L-thyroxine in vitro by Peripheral Leukocytes from Rhesus Monkeys with Bacterial Sepsis

Abstract : The deiodination of l-thyroxine (T4) in vitro by peripheral leukocytes isolated from healthy rhesus monkeys was compared to that of leukocytes from monkeys with acute Salmonella typhimurium sepsis, an infection associated with accelerated metabolism of T4 in vivo. Deiodination of T4 by leukocytes from septic monkey donors was significantly enhanced, with inorganic iodide identified chromatographically as the predominant product of T4 degradation. Induction of phagocytosis in vitro potentiated the T4 deiodinating activity of leukocytes from both control and infected monkeys. However, the proportion of added T4 degraded by leukocytes from septic donors following stimulation of phagocytosis in vitro was nearly twice that of cells from controls. The data suggest that deiodination of T4 by host neutrophils might contribute to the acceleration of T4 metabolism observed in vivo during some acute infections. (Modified author abstract)