Murine hypodense eosinophils induce tumour cell apoptosis by a granzyme B-dependent mechanism |
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Authors: | Costain D J Guha A K Liwski R S Lee T D |
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Institution: | (1) Faculty of Medicine, Department of Pathology,Dalhousie University, Halifax,Nova Scotia, Canada, CA;(2) Transplantation and Immunology Research Laboratory, Departments of Surgery and Microbiology and Immunology, Room 10A, Sir Charles Tupper Medical Building, Faculty of Medicine, Dalhousie University, Halifax, B3H 4H7, Nova Scotia, Canada e-mail: tim.lee@dal.ca Tel.: +1-902-4943882; Fax: +1-902-4945125, CA |
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Abstract: | Purpose: Eosinophils have been shown to potentiate anti-tumour cytotoxicity in both clinical and animal studies. The mechanism by
which eosinophils induce tumour cell damage, however, has largely been speculative. The purpose of this study was to identify
the mechanisms involved in eosinophil-induced tumour cell cytotoxicity. Methods: To investigate eosinophil cytotoxicity, eosinophils were isolated from the peritoneal cavity of Mesocestoides corti-infected BALB/c mice, and were separated into normodense (ND) and hypodense (HD) populations using discontinuous Percoll
density gradient centrifugation. The tumoricidal activity of ND and HD eosinophils was assessed using the 51Cr]-release cytotoxicity assay (a measure of cytolytic activity) and the JAM assay (a measure of apoptotic activity). Investigation
of apoptosis-inducing molecules in HD eosinophils was undertaken by RT-PCR. The calcium chelator EGTA, serine protease inhibitor
aprotinin and a competitive substrate for granzyme B were used to assess the role of perforin and granzyme B in HD eosinophil
killing. Results: Cytotoxic activity induced by HD eosinophils was significantly greater than that of ND eosinophils, and apoptosis was the
principal killing mechanism. RT-PCR analysis revealed that HD eosinophils express mRNA for perforin, granzyme B and Fas ligand.
Furthermore, HD eosinophil killing was markedly inhibited by EGTA, intracellular aprotinin and the granzyme B competitive
substrate. Conclusions: These data are consistent with a hypothesis that murine HD eosinophils elicit tumoricidal activity via a granzyme B-dependent
mechanism.
Received: 28 January 2001 / Accepted: 25 April 2001 |
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Keywords: | Hypodense Eosinophil Apoptosis Granzyme B Perforin |
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