[Kinetics and immunocytochemical staining of 99mTc-labeled monoclonal anti-CEA antibodies against granulocytes following intravenous administration].

Until now the clinical identification of the affinity of monoclonal 99mTc-anti-CEA antibodies (MAK BW 250/183) on granulocytes was made with tumor cells carrying the same epitope on NCA-95 and human granulocytes in vitro. As this antibody only binds human granulocytes, animal experiments are impossible. 3 patients had their blood withdrawn within 6 h after injection, another patient had his left hip-joint biopsied after 24 h, the samples undergoing subsequent immunocytochemical dyeing. Dyeing of granulocytes all over the smears was evident whereas lymphocytes, monocytes and erythrocytes did not show any reaction. After 6 h there seemed to be a large difference between a relatively high quantity of 86% unlabelled 99mTc-MAb and 75% of immunocytochemically stainable granulocytes in the blood through an excess of binding epitopes. Six h after injection 27% of the activity were, on average, detectable in whole blood. At this time the activity in blood was reduced to an extent that scintigraphic imaging was feasible.