RT Journal Article SR Electronic T1 Labeling of Mixed Leukocytes with 99mTc-HMPAO Causes Severe Chromosomal Aberrations in Lymphocytes JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 203 OP 206 VO 43 IS 2 A1 İlknur Ak A1 Erkan Vardereli A1 Beyhan Durak A1 Zafer Gülbaş A1 Nurettin Basaran A1 Marcel P.M. Stokkel A1 Ernest K.J. Pauwels YR 2002 UL http://jnm.snmjournals.org/content/43/2/203.abstract AB 99mTc-d,1-hexamethylpropyleneamine oxime (HMPAO) is widely used as a labeling agent for leukocytes in the diagnosis of inflammatory or infectious foci. Cytotoxicity studies have indicated that intracellular labeling of leukocytes with 111In compounds may have severe detrimental effects on the cells. Methods: In this study, the radiotoxic effects on mixed lymphocytes after labeling with 99mTc-HMPAO was investigated using the cytokinesis-blocked micronucleus assay and chromosomal aberration assay. Results: Whereas negligible numbers of chromosome abnormalities were noted in unlabeled lymphocytes, the labeled lymphocytes showed multiple aberrations of various types, including dicentric, tricentric, and fivecentric chromosomes; centric rings; chromosome and chromatid type breaks; and acentric fragments. Conclusion: Heavily aberrant lymphocytes are seen in 99mTc-HMPAO–labeled mixed leukocytes after routine clinical procedures. It is unlikely, however, that this would cause detrimental effects, such as lymphoid malignancy, as these cells would normally be eliminated through apoptosis or phagocytosis.