Deposition of Beef Serum Gamma-Globulin in Rabbit Organs and Subcellular Fractions

Abstract

Rabbits injected with beef serum γ-globulin, which had been coupled with very small amounts of diazotized S³⁵-sulfanilic acid, were sacrificed at intervals of time from 15 minutes to 93 days, and their organs assayed for residual trichloroacetic acid precipitable radioactivity. The distribution of radioactivity among the subcellular fractions isolated by differential centrifugation from spleen and liver homogenates was also determined. A high concentration of the labeled globulin persisted in the blood until 4–5 days after injection, when there was an abrupt decline due to the onset of antibody formation. After 7.5 days, the levels of globulin in all the organs investigated, except heart, were much higher than the blood level. By the 93rd day, most of the organ levels had fallen only to about a third of the high levels at 7.5 days. Evidently, antibody formation is initiated and continues in the presence of deposited antigen. The beef globulin undergoes a brief initial deposition in the microsomal fraction of the liver, but soon becomes nearly evenly distributed among all fractions of the perfused liver. With the abrupt fall in the blood level of antigen accompanying antibody formation, there is a decrease in the relative activity of the supernatant fraction, and an increase in the relative concentration of antigen in the mitochondrial fraction of both liver and spleen, suggesting that the components of this subcellular fraction may be involved in the process of antibody formation.