Serum protein changes in monkeys infected with Schistosoma mansoni, with special reference to the metabolism of albumin

Abstract

1. 1. Studies have been carried out on the serum protein changes in seven rhesus monkeys infected with Schistosoma mansoni, using the biuret method of protein determination and paper electrophoresis. On three of these monkeys, the blood volume and the distribution and metabolism of albumin were investigated simultaneously, using homologous 131I-Iabelled albumin. 2. 2. A sudden change in the concentration of the serum proteins occurs 6 to 7 weeks after the initial infection, i.e., about the time when eggs first appear in the faeces. The change consists of an increase in gamma-globulin concentration; usually an increase in total protein concentration; and, at least in heavy infections, a decrease in albumin concentration; in some monkeys there is a rise in the beta globulin concentration. When resistant monkeys are “challenged” with large numbers of cercariae, similar changes occur earlier, i.e., 2 weeks after exposure. 3. 3. The isotope studies show that associated with the serum protein changes there is a fall of total body and intravascular albumin with a subsequent rapid recovery, and a marked increase in the intravascular albumin “catabolic” rate, followed by a slow return to normal. Between the 8th and 12th week of infection there is an increase in the albumin distribution ratio, signifying an increase in the size of the extravascular pool of albumin; this is followed by a slow return to normal. 4. 4. It is believed that the fall in albumin is due to a sudden increase in albumin catabolism incompletely compensated by an increase in anabolism.