Phagocytosis of Heterologous Red Cells in Mice Injected with Isologous Microsomes. ∗

Summary

1. Parenteral administration to mice of homogenates, and particularly of microsomal fractions, prepared from isologous liver, spleen, or kidney, caused a significant reduction in hepatic and splenic uptake of subsequently injected Cr⁵¹-labeled sheep red cells. 2. These changes in r.e. phagocytosis were transient, but they were also observed at certain stages of long-term administration of the tissue fractions. 3. The biologic activity did not appear to be related to the N content of the substrates, but rather to the RNA content. 4. No untoward effects on the health of the mice were encountered, and the only gross changes attributable to the treatment were moderate increases in size of liver and spleen. 5. The possible significance of the changes in r.e. phagocytosis and their relationship to previous work have been discussed.