The Fate in Guinea-Pigs of Intraven-ously Injected I131-γ-Globulin

1) The fate and rate of degradation of I131 labelled rabbit γ-globulin, which retained its native antigenicity and antibody specificity was studied in the guinea-pigs. 2) Blood elimination rate of heterologous γ-globulin is higher than that of homologous γ-globulin. 3) Denatured and digested γ-globulin departs from the blood more rapidly than the native one, and urinary excretion rates of denaturated and digested γ-globulin are higher than that of the native one. It is inferred, therefore, that the denatured and digested γ-globnlin is more liable to be resolved and decomposed in the reticulo-endothelial organs than the native one. And the value obtained from the urinary excretion reflects the rate of protein break down in some cellular compartments. 4) Following the plasmaphresis the increase in antigen elimination was lessened and delayed as compared with control animals. 5) The organ distribution of heterologous I131-γ-globulin is to the lymphnode> the spleen> the liver> the lung> the kidney> the intestine in descending order. Heterologous I 131 -γ- globulin is deposited in greater quantity in the reticulo-enclotherial organ than other single organ. 6) Following the intravenous injection of I131 labelled antigens, the ratio of the specific activity of mitochondria and microsom to that of whole liver homogenate was determined over a period from 15 minutes to 3 hours in guinea-pigs, and following results were obtained. a) Organ and intracellular distribution of Il3l labelled homologous γ-globulin shows no great difference compared to that of heterologous one. b) The intracellular distribution of heterologous γ-globulin is in mitochondrial> microsomal> nuclear fraction in descending order. c) The heterologous γ-globulin quantity of mitochondrial fraction or microsomal fraction in the spleen is higher than that of the liver. 7) The antibody distribution of intracellular glanules measured in terms of radioactivity with a Geiger-Muller counter, after the reaction of I131 labelled antigen. The quantity of distribution of intracellular glanules decreases in mitochondrial fraction> microsomal fraction> nuclear fraction in descending order.