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H. Qiao, J. Stein–Streilein; "Surrogate" Eye–Derived APC Signal a Subset of iNKT Cells Toward Tolerance . Invest. Ophthalmol. Vis. Sci. 2005;46(13):997.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: NKT cells are innate immune cells that are capable of responding to danger with secretion of cytokines within minutes–hours. NKT cells are also critical for the development of anterior associated immune deviation (ACAID) and the generation of efferent antigen specific CD8+ T regulatory (Tr) cells that suppress T effector cells responses. Here we compare and contrast the response of invariant (i) NKT cells (hybridoma and ex–vivo cells) to tolerogenic versus immunogenic antigen–presenting cells (APC) to understand if there is a common precursor of iNKT cells that responds differently depending the APC signals or if subpopulations of iNKT cell have a predetermined functions. Methods: In vitro: NKT hybridoma (DN32.D3) cells were cultured with TGF–ß and OVA pulsed thioglycolate–induced–peritoneal exudate cells (PEC) or LPS treated PEC. The DN32.D3 cells were collected 30 min. and 1 h after stimulation. In vivo: CD4+ NKT cells were enriched by FACS sorting of spleen cells harvested from Class II KO, WT or NKT cell transgenic mice, 7 D after OVA a.c. injection. Semiquantitative analyses of mRNA were performed by competitive RT–PCR. Results: Following exposure to tolerogenic APC, DN32.D3 cells increased their production of RANTES mRNA (30 min) and IL–10 mRNA (1h) but decrease their production of message for IFN–γ (1h). There was no difference in the mRNA for these cytokines in NKT Cells incubated with unmanipulated or LPS treated PEC. Furthermore, we observed that RANTES mRNA levels were increased and IFN–γ were suppressed in a subpopulation of iNKT cells harvested from WT or Class II KO mice that expressed CD4 and Ly49C proteins. Conclusions: We conclude that the phenotype of the APC orchestrates the regulatory function of the iNKT cells. However, the response is also dependent on the phenotype of the NKT cells since not all NKT cells responded with up–regulation of RANTES. Thus we predict that both APC and the NKT cells with unique phenotypes must interact to effect the tolerogenic function that leads to CD8+ Tr cells in tolerance induced through the eye.
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