Biodistribution of (111)indium-labeled macrophages infused intravenously in patients with renal carcinoma

Purpose: We have previously reported a clinical trial on the intravenous in jection of autologous activated macrophages (AAM) in 15 patients with renal carcinoma [11]. The present paper concerns scintigraphic investigations pe rformed in I I of these patients after injection of (111)indium oxinate-rad iolabeled AAM. Methods: AAM were prepared from mononuclear cells (MNC) coll ected by apheresis from patients treated simultaneously with granulocyte-ma crophage colony-stimulating factor (GM-CSF). MNC were cultured for 6 days i n the presence of GM-CSF and exposed for 18 h to gamma-interferon, the AAM were then separated by elutriation and injected. Results: After intravenous infusion, radiolabeled AAM were transiently retained in the lungs, where t hey predominated in the first hour. Later on, radioactivity accumulated in liver and spleen and then decreased from the first and second day, respecti vely. In one patient, two foci of radioactivity were detected in the lungs I h after injection, and persisted thereafter. Their association with tumor lesions was uncertain. This observation possibly resulted from the presenc e of granulocytes in the radiolabeled AAM populations of this patient. It s eems that MNC collected from GM-CSF-treated patients and cultured in the pr esence of GM-CSF enables the differentiation of granulocytes. Conclusions: A series of 11 investigations confirms the previously reported distribution pattern of intravenously injected AAM. It is possible that in patients tre ated with hematopoietic cell-mobilizing agents, granulocytes develop in cul tures designed to produce monocyte-derived antigen-presenting cells.