Activated Vγ9Vδ2 T cells, the major γδ T lymphocyte subset in humans, show cytolytic activity against various tumor cells. However, tumor antigens recognized by the TCR remained unkown so far. Recently, the ectopic surface expression of the F1-ATPase, normally expressed on the internal membrane of mitochondria, was implicated in tumor recognition of Vγ9Vδ2 T cells (

Scotet E. et al.,
Immunity
2005
;
22
:
71
–80
). Surface expression of the a chain of the F1-ATPase (recognized by monoclonal antibody 7H10) strongly correlates with susceptibility of tumor cells against Vγ9Vδ2 T cell lysis. Different functions have been attributed to the ectopic expression of the F1-ATPase on the cell surface, including an immunoregulatory role induced by cell stress, receptor for angiostatin or regulation of lipoprotein transport through high-affinity apolipoprotein A-I binding. In this study we evaluated the surface expression of this F1-ATPase on hematopoetic tumor cell lines and on primary tumor cells from hematological malignancies. As already shown, the a subunit of F1-ATPase was clearly detected on several tumor cell lines which are consistently killed by activated Vγ9Vδ2 T cells (Daudi, K562, RPMI 8226), whereas the known Vγ9Vδ2 T cell resistant tumor cell lines (Raji, Jurkat) did not express detectable levels of the F1-ATPase. Analysis of 42 primary hematopoetic tumor cells (21 myeloma, 17 AML, 4 B-NHL) revealed frequent expression of F1-ATPase on primary myeloma cells (14/19 positive), whereas primary AML blasts (3/17 positive) and primary NHL cells (1/4 positive) expressed the putative Vγ9Vδ2-TCR ligand F1-ATPase less frequently. To further evaluate the functional role of F1-ATPase expression in Vγ9Vδ2 T cell mediated recognition of myeloma cells, cytotoxicity assays were performed. The mAb against the a subunit of F1-ATPase significantly decreased in vitro lysis of myeloma cells lines and primary myeloma cells by activated Vγ9Vδ2 T cells. These results suggests Vγ9Vδ2 TCR-dependent interactions between myeloma cells and Vγ9Vδ2 T cells and indicate that multiple myeloma should be considered as a major target for γδ T-cell mediated immunotherapy.

Topics:
adenosine triphosphatases, immunotherapy, ligands, multiple myeloma, myeloma cells, t-lymphocytes, tumor cells, monoclonal antibodies, angiostatins, apolipoprotein a-i

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2005, The American Society of Hematology
2005
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