In vivo studies of 111In-labelled canine lymphocytes

[111In]oxine was used to label canine periperal blood lymphocytes from two normal animals and one animal with breast carcinoma. Using 150 microCi of [111In]oxine to label 50 X 10(6) cells yielded a labeling efficiency between 40 and 75% and a viability of about 95%. Gamma camera images obtained 24-44 h after injection showed uptake in the subcutaneous lymph nodes of the head, neck, axilla, pelvis and popliteal regions. Uptake in the liver, spleen, bowel, and bone marrow was also seen. In the animal bearing breast carcinoma, uptake occurred in the tumor, lungs and in a draining sinus in the left axilla. These results suggest that 111In labeled lymphocytes are useful in visualizing regional lymph nodes and may be valuable in assessing tumor recognition by these cells in vivo.