Human V␣24 NKT cells bearing an invariant V␣24J␣Q antigen receptor, the counterpart of murine V␣14 NKT cells, are activated by a specific ligand, ␣-GalCer, in a CD1d-dependent manner. Here, we demonstrate decreased numbers of circulating V␣24 NKT cells in patients with primary lung cancer compared to healthy volunteers. However, V␣24 NKT cells and DCs from lung cancer patients were functionally normal, even in the presence of tumor. Furthermore, levels of V␣24 NKT cells in surgically resected lung tissue appeared to be equivalent to those of V␣14 NKT cells in the mouse lung. Levels of V␣24 NKT cells in the tumor tissue itself were increased about 2.5 times. Administration of ␣-GalCer-pulsed DCs expanded V␣14 NKT cells in the lung more than 10 times, and the increased levels were sustained for 1 week. This may explain the previous finding that ␣-GalCer-pulsed DCs exerted strong antitumor activity in mouse lung tumor metastatic models. The potential use of ␣-GalCer-pulsed DCs for immunotherapy aimed at activating endogenous V␣24 NKT cells in the lung of cancer patients is discussed. © 2002 Wiley-Liss, Inc.
Key words: V␣24 NKT cell; IFN-␥ primary lung cancer; ␣-galactosylceramide; single-cell sorting RT-PCRMurine V␣14 NKT cells are characterized by coexpression of NK1.1, an NK cell marker, and an invariant antigen receptor encoded by V␣14 and J␣281 gene segments. 1-3 V␣14 NKT cells recognize a glycolipid, ␣-GalCer, in a CD1d-depenent fashion. 4 The CD1d molecule has been well conserved throughout mammalian evolution and lacks allelic polymorphism. 5-7 After activation, V␣14 NKT cells inhibit tumor metastasis in certain experimental animal models. 8 -10 Furthermore, i.v. injection of ␣-GalCer-pulsed DCs expressed a potent antitumor effect in a B16 melanoma liver metastasis model, where metastasized tumor nodules were eradicated. 11 Human NKT cells bearing the invariant V␣24J␣Q receptor are considered to be the counterpart of murine V␣14 NKT cells and may recognize antigens similar to those of murine V␣14 NKT cells because of striking homology between human V␣24 and mouse V␣14 receptors, particularly in their complementarity-determining region 3. 2 Indeed, human V␣24 NKT cells were activated by ␣-GalCer in a CD1d-dependent fashion 5,12,13 and showed strong antitumor activity upon ␣-GalCer stimulation. 14,15 Human V␣24 NKT cells play crucial roles in various immune responses, including antitumor and autoimmune responses. 16 -19 These reports demonstrated selective reduction in V␣24 NKT cell numbers. Little is known, however, about the nature of V␣24 NKT cells in primary lung cancer patients.We investigated the function of V␣24 NKT cells in peripheral blood and lung of patients with lung cancer. The numbers of V␣24 NKT cells were reduced, whereas the function of freshly isolated V␣24 NKT cells appeared to be preserved in tumor-bearing patients. Furthermore, the ability to present ␣-GalCer by patient DCs was within a normal range. Administration of ␣-GalCer-pulsed DCs expanded V␣14 NKT cells in the lung more than 10 ti...