The Effects of (99mTc) Hm-Pao Labeling on Lymphocyte Functions

Objective: (99mTc) HM-PAO labeled leucocytes have been used as a standard diagnostic procedure for the detection of infection and inflammation. Although, some investigators have already pointed out that labeling of leucocytes with (99mTc) HM-PAO has detrimental effects on the cells, still very little is known regarding the effects of ionizing radiation on lymphocyte functions. Methods: In this study, we evaluated the effects of (99mTc) HM-PAO labeling on lymphocyte adhesion, proliferation, migration and apoptosis. We used NC-NC lymphoblastoid cell line as the lymphocyte population. (99mTc) HM-PAO labeling decreased cell adhesion, proliferation and motility whereas induced apoptosis, and cell cycle arrest. Proliferation assays were performed both using MTT and ELISA tests with 24 hours intervals following labeling. Results: It was recorded that the rate of decrease in proliferation was up to 70% by the 4th day after labeling. (99mTc) HMPAO labeling led a 35% decrease on adhesion ability of the cells on fibronectin. By using Boyden chamber motility assay, we showed that both spontaneous and MCP-1 induced lymphocyte motility were potently blocked by (99mTc) HM-PAO labeling. The rate of decrease in motility was approximately five times. In addition, we observed a 12 times increase in the apoptosis rate within the (99mTc) HM-PAO treated cells compared to the control cells. Besides it was observed that cell cycle arrest was induced starting from 3rd day after (99mTc) HM-PAO treatment. Conclusion: Based on our data (99mTc) HM-PAO labeling has damaging effects on lymphocyte functions including cell adhesion, proliferation, motility and viability in in vitr