Labeling of phagocytes from human blood with 99mTc-sulfur colloid

Experments in this report have shown that peripheral blood leukocytes can be readily labeled with 99mTc-sulfur colloid during in vitro incubation. Phagocytic cells were preferentially labeled by this method. Labeling was enhanced in the presence of normal serum. The data suggest that labeling was accomplished by phagocytosis of the radiocolloid. Labeled granulocytes responded normally to chemotactic stimuli and excluded trypan blue dye normally. Buffy coat cells from 50 ml of peripheral blood could be labeled with 8 mCi of 99mTc after incubation with 20 mCi of TcSC. This report offers a method by which phagocytic cells can be selectively labeled with 99mTc in amounts suitable for scintillation scanning.