krn-7000 and Pleural-Effusion--Malignant

CD1d-restricted natural killer T (iNKT) cells have been shown to provide adjuvant activity against cancer by producing interferon (IFN)-γ. However, the role of invariant NKT (iNKT) cells in the tumor microenvironment has not yet been fully addressed. Our aim is to elucidate the antitumor effect of iNKT cells in the tumor microenvironment by using an intrathoracic murine malignant pleural mesothelioma model that we had previously developed and to provide pleural effusion as a good surrogate of the tumor microenvironment. We found that the number of iNKT cells increased dramatically in the pleural effusion after intrathoracic tumor cell injection at an earlier phase compared with accumulation of CD8 T cells. These iNKT cells showed increased expression of CD25 and increased ratio of cells positive for IFN-γ intracellular staining. iNKT cells sorted from pleural effusion of tumor burden mice produced larger amount of IFN-γ compared with naive mice. Mice pretreated in vivo with anti-CD1d-blocking Ab showed increased amount of pleural effusion and decreased ratio of total and effector-type CD8 T cells as well as decreased intracellular IFN-γ expression of CD8T-cell in the pleural effusion. In vivo administration of α-galactosylceramide (α-GalCer) showed prolonged survival associated with less pleural effusion and increased ratio of IFN-γ-positive iNKT cells and CD8 T cells in the pleural effusion. Therefore, this study suggests that iNKT cells accumulating in the tumor microenvironment play an antitumor effect by producing IFN-γ and enhancing subsequent CD8 T-cell response. Furthermore, in vivo administration of α-GalCer could suppress mesothelioma growth by activating iNKT cells.

Topics: Animals; Antibodies, Blocking; Antigens, CD1d; CD8-Positive T-Lymphocytes; Cell Growth Processes; Cell Line, Tumor; Female; Galactosylceramides; Interferon-gamma; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Mice; Mice, Inbred BALB C; Natural Killer T-Cells; Neoplasm Transplantation; Pleural Effusion, Malignant; Pleural Neoplasms; Tumor Burden; Tumor Microenvironment

Valpha24NKT cells are lymphocytes expressing both T-cell antigen receptors and NK-cell antigen receptors on their cell surface and are involved in tumor immunity. They exert their antitumor effects after being activated by a specific ligand, alpha-galactosyl ceramide (alpha-GalCer). Malignant pleural effusion, a frequently occurring complication in patients with lung cancer, contains numerous lymphocytes. In the present study, we examined the presence and functions of Valpha24NKT cells in the lymphocytes in pleural effusion in vitro. The subjects were 13 untreated patients with primary lung cancer, who suffered malignant pleural effusion as a complication and who were treated between April 2004 and October 2007 at our hospital. Mononuclear cells were separated from the malignant pleural effusion and incubated with alpha-GalCer and IL-12. The production of IFN-gamma and IL-4 after incubation and the proportion of the Valpha24NKT cells before and after incubation were determined and compared. In the group cultured with alpha-GalCer alone, no significant increase in IFN-gamma production was observed in comparison with the control group. In the group cultured with alpha-GalCer+IL-12, IFN-gamma production increased significantly in comparison with the control group, and the proportion of Valpha24NKT cells increased after incubation. IL-4 production was very much lower than IFN-gamma production. Valpha24NKT cells were present in malignant pleural effusion in patients with lung cancer, but IFN-gamma production did not increase after addition of alpha-GalCer alone. The Valpha24NKT cells were activated by alpha-GalCer in the presence of IL-12. The Valpha24NKT cells in malignant pleural effusion were not activated by alpha-GalCer alone, suggesting that Valpha24NKT cell function is attenuated in malignant pleural effusion.

Topics: Adult; Aged; Antigens, CD; CTLA-4 Antigen; Female; Galactosylceramides; Humans; Interferon-gamma; Interleukin-12; Interleukin-2 Receptor alpha Subunit; Interleukin-4; Killer Cells, Natural; Lung Neoplasms; Lymphocyte Activation; Male; Middle Aged; Pleural Effusion, Malignant; Receptors, Antigen, T-Cell, alpha-beta