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99m Tc‐HMPAO (Ceretec) is stored in and released from the granules of eosinophil granulocytes
Author(s) -
Moberg Lena,
Karawajczyk Malgorzata,
Venge Per
Publication year - 2001
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.2001.02889.x
Subject(s) - percoll , eosinophil , eosinophil cationic protein , granulocyte , organelle , granule (geology) , myeloperoxidase , chemistry , cytochemistry , immunology , centrifugation , microbiology and biotechnology , biology , biochemistry , inflammation , enzyme , paleontology , asthma
99m Tc‐HMPAO (Ceretec) labelling of leucocytes is used clinically for the detection of inflammatory processes in the body. This study investigated the mechanisms by which 99m Tc‐HMPAO is taken up by eosinophils and neutrophils. Blood cells were labelled with 99m Tc‐HMPAO and the cells separated by means of their densities in Percoll gradients. For other purposes, eosinophils and neutrophils were purified by means of the MACS system and, after labelling these pure cellular preparations, the cells were ultrasonicated and the organelles separated on sucrose density gradients by means of ultracentrifugation. Organelles were characterized by their morphology on electron microscopy. Granulocytes were stimulated to secrete their granule constituents by means of exposure to complement‐coated particles. ECP (eosinophil cationic protein) and MPO (myeloperoxidase) were measured using specific immunoassays. The uptake of 99m Tc‐HMPAO was 15–25‐fold higher in eosinophils than in other leucocytes. 99m Tc‐HMPAO was predominantly stored in the secretory granules of eosinophils and released from the eosinophil, upon activation, together with ECP. A second storage compartment was a very light density organelle of unknown nature. These results indicated that, among leucocytes, 99m Tc‐HMPAO is preferentially taken up by eosinophils and stored in the secretory granules, which has to be taken into consideration when evaluating images based on this technique. Our findings suggest that 99m Tc‐HMPAO (Ceretec) may be used as a tool to follow eosinophil turnover and activity in disease.