Evidence for the in Vivo Localization of Heterologous Anti-Leukocyte and Anti-Bone Marrow Antibodies in the Rat Bone Marrow

1. The intravenous injection of I¹³¹-labeled heterologous anti-leukocyte and anti-bone marrow antibodies into rats resulted in a high specific in vivo localization in the bone marrow, indicating the presence of localizing anti-body.

2. No in vivo localization in lungs was demonstrated, in possible contrast to the earlier concept of pulmonary emboli of clumped leukocytes sensitized with antibodies in experimental immunoleukopenia.

3. Heterologous anti-leukocyte and anti-bone marrow antibodies injected intravenously disappeared from plasma and fixed to peripheral leukocytes and bone marrow cells within 1 hour.