Tc-99m-HMPAO uptake by bronchoalveolar cells

Lung uptake of intravenously injected Tc-99m-HMPAO is observed in smokers and in lung toxicity due to various agents. We investigated the Tc-99m-HMPAO uptake of bronchoalveolar lavage (BAL) cells in the lungs after incubation in in vitro conditions (6 patients), intravenous injection (IV) (7 patients) and inhalation (INH) (6 patients) of Tc-99m-HMPAO in order to show whether BAL cells are also responsible for Tc-99m-HMPAO uptake in the lungs. Cell/supernatant (C/S) count ratio was 7.0±3.5, 29.3±40.8 and 8.4±4.5 for in vitro, IV and INH groups, respectively. C/Sinvitro showed a positive correlation with % alveolar macrophages (r=0.943, p=0.0048) and a negative correlation with % neutrophils (r=-0.945, p=0.0045). Cells/whole BAL fluid ratio correlated with the amount of daily cigarette consumption in INH group (r=0.95, p= 0.0037). Tc-99m-HMPAO showed adherence to mucus after inhalation. Tc-99m-HMPAO diffuses into alveolar spaces after injection and is present in BAL fluid and BAL cells both after injection and inhalation. Glutathione concentration and oxido-reductive state of the epithelial lining fluid and BAL cells may influence the lung uptake of Tc-99m-HMPAO. (author)