Distribution studies of 111In-oxine-labeled peritoneal mononuclear cells in tumor-bearing rats

We studied the distribution of 111In-labeled peritoneal mononuclear cells (PMC) in Sprague-Dawley rats with carcinosarcoma (CS) tumor. We obtained PMC from normal rats and rats pretreated with BCG or irradiated CS cells as antigenic stimulant. PMC were labeled in-vitro with 111In-oxine and transferred by tail-vein injection to rats bearing CS tumor. Twenty-four, 48 and 72 h after PMC transfer, we measured the accumulation of these cells in the CS tumor as a percentage of dose radioactivity per gram of tumor using an external gamma-ray camera. PMC from normal and BCG treated donor rats accumulated 0.4% and 0.46% dose per gram of CS tumor respectively. PMC from donor rats given killed CS cells accumulated significantly greater concentrations of 111In (0.79% dose per gram of CS tumor, P less than 0.025). Thus killed CS cells were able to sensitize the PMC of normal rats. 111In-oxine-labeling is an elegant procedure to study the distribution of mononuclear cells in tumors.