LABELING LYMPHOCYTES WITH TECHNETIUM(99M) HEXAMETHYL PROPYLENEAMINE OXIME FOR SCINTIGRAPHY - AN IMPROVED LABELING PROCEDURE

Leukocyte scintigraphy has been used as a standard diagnostic procedur e for the detection of inflammation in vivo. In this study, we develop ed a method of labelling purified lymphocytes with technetium(99m)-hex amethyl propyleneamine oxime (Tc-99m-HMPAO) without significantly impa iring their function. This was confirmed by measurements of in vitro l ymphocyte adhesion and migration and of both necrotic and apoptotic ce ll death. The results of the in vitro control studies indicate that th e dysfunction of leukocytes caused by Tc-99m-HMPAO labelling can be mi nimized by using a gentle labelling method and low Tc-99m activity. Be cause lymphocytes have been thought to participate specifically in the pathogenesis of inflammatory bowel disease (IBD), we compared scintig raphies obtained with Tc-99m-HMPAO-labelled purified lymphocytes and m ixed leukocytes in colitis patients. We found that a lower number of T c99m-HMPAO-labelled peripheral blood lymphocytes accumulated in the in flamed colon during the first 4 h than labelled mixed leukocytes. The results are likely to reflect the dissimilar kinetics of lymphocyte tr affic compared with granulocytes in LED. We do not recommend the use o f Tc-99m-HMPAO-labelled purified lymphocytes as a diagnostic tool in c hronic colitis. However, the in vitro data indicate that Tc-99m-HMPAO- labelled lymphocytes may be suitable for studying short term lymphocyt e recirculation and lymphocyte kinetics in other types of inflammation . (C) 1998 Elsevier Science B.V All rights reserved..