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

Purpose: We have previously reported a clinical trial on the intravenous injection of autologous activated macrophages (AAM) in 15 patients with renal carcinoma [11]. The present paper concerns scintigraphic investigations performed in 11 of these patients after injection of 111indium oxinate-radiolabeled AAM. Methods: AAM were prepared from mononuclear cells (MNC) collected by apheresis from patients treated simultaneously with granulocyte–macrophage colony-stimulating factor (GM-CSF). MNC were cultured for 6 days in 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 they predominated in the first hour. Later on, radioactivity accumulated in liver and spleen and then decreased from the first and second day, respectively. In one patient, two foci of radioactivity were detected in the lungs 1 h after injection, and persisted thereafter. Their association with tumor lesions was uncertain. This observation possibly resulted from the presence of granulocytes in the radiolabeled AAM populations of this patient. It seems that MNC collected from GM-CSF-treated patients and cultured in the presence 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 treated with hematopoietic cell-mobilizing agents, granulocytes develop in cultures designed to produce monocyte-derived antigen-presenting cells.