Labelling lymphocytes with technetium99m hexamethyl propyleneamine oxime for scintigraphy:: an improved labelling procedure

Leukocyte scintigraphy has been used as a standard diagnostic procedure for the detection of inflammation in vivo. In this study, we developed a method of labelling purified lymphocytes with technetium(99m)-hexamethyl propyleneamine oxime (Tc-99m-HMPAO) without significantly impairing their function. This was confirmed by measurements of in vitro lymphocyte adhesion and migration and of both necrotic and apoptotic cell death. The results of the in vitro control studies indicate that the dysfunction of leukocytes caused by Tc-99m-HMPAO labelling can be minimized by using a gentle labelling method and low Tc-99m activity. Because lymphocytes have been thought to participate specifically in the pathogenesis of inflammatory bowel disease (IBD), we compared scintigraphies obtained with Tc-99m-HMPAO-labelled purified lymphocytes and mixed leukocytes in colitis patients. We found that a lower number of Tc99m-HMPAO-labelled peripheral blood lymphocytes accumulated in the inflamed colon during the first 4 h than labelled mixed leukocytes. The results are likely to reflect the dissimilar kinetics of lymphocyte traffic compared with granulocytes in LED. We do not recommend the use of Tc-99m-HMPAO-labelled purified lymphocytes as a diagnostic tool in chronic colitis. However, the in vitro data indicate that Tc-99m-HMPAO-labelled lymphocytes may be suitable for studying short term lymphocyte recirculation and lymphocyte kinetics in other types of inflammation. (C) 1998 Elsevier Science B.V All rights reserved..