title: Ablation of NK cell function during tumor growth favors Type 2-associated macrophages, leading to suppressed CTL generation.
abstract: Several reports describe regulatory interactions between NK cells and CTLs. We addressed the issue of NK participation in the early anti-tumor defense by inoculating alpha-ASGM-1 treated mice with BW-Sp3 T lymphoma. Rejection of BW-Sp3 depends on strong CTL responses. Our results demonstrated that (i) NK cells are a prerequisite for efficient CTL generation and (ii) the absence of NK cells favors the outgrowth of alternatively activated macrophages that can suppress CTL restimulation. In vitro studies demonstrate that in splenic cultures from NK-deficient, tumor-bearing mice, the presence of alternatively activated macrophages correlates with a lack of Type 1 cytokines, while the production of Type 2 cytokines is promoted. Provision of the Type 1 cytokine, IFN-gamma can boost overall CTL activity but does not revert the dominance of arginase producing adherent cells in the NK-deficient CTL cultures. The role of NK effector functions in the efficient switch of the immune system towards Type 1 activation was evaluated in cytotoxicity assays. The results indicate that the accessory function of NK can depend at least partially on their ability to preferentially engage arginase-producing cells, suggesting that NK/macrophage lytic interactions might be involved in the switch from Type 2 to Type 1-dependent immune responses.
authors.affiliation: Laboratory of Cellular Immunology, Free University of Brussels, Flemish Interuniversity Institute for Biotechnology, B-1640 St.-Genesius Rode, Belgium. ageldhof@cntnl.jnj.com
authors.forename: Anja B
authors.initials: AB
authors.lastname: Geldhof
authors.forename: Jo A
authors.initials: JA
authors.lastname: van Ginderachter
authors.forename: Yuanqing
authors.initials: Y
authors.lastname: Liu
authors.forename: Wim
authors.initials: W
authors.lastname: Noël
authors.forename: Patrick
authors.initials: P
authors.lastname: de Baetselier
mesh_terms: D000818:Animals; D039481:CD11b Antigen / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D016207:Cytokines / Q000276:immunology*; D018450:Disease Progression; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000276:immunology / Q000473:pathology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000187:drug effects / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*
chemical_list: D039481:CD11b Antigen; D016207:Cytokines; D007371:Interferon-gamma