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Description:
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To examine how dietary n -3 polyunsaturated fatty acids affect Th2 cell development , female C57BL /6 mice were fed a washout corn oil (CO ) diet for 1 wk followed by 2 wk of either the same CO diet or a fish oil (FO ) diet . CD4+ T cells were isolated from spleens and cultured under both neutral (anti -CD3 and phorbol myristate acetate (PMA ) ) and Th2 polarizing conditions (anti -CD3 and PMA , in presence of rIL -4 , rIL -2 , and anti -IFN -à ³ ) in the presence of homologous mouse serum (HMS ) or fetal bovine serum (FBS ) for 2 d . Dietary n -3 PUFA significantly enhanced Th2 cell development and suppressed Th1 development under neutral conditions as assessed by intracellular cytokine staining for IL -4 and IFN -à ³ as the two prototypic Th2 and Th1 cytokines , respectively . However , under Th2 polarizing conditions , while the suppression of Th1 cells was maintained in FO -fed mice , no dietary effect was observed in Th2 cells . Dietary FO increased the Th2 /Th1 ratio under both neutral and Th2 polarizing conditions with HMS in the cultures . To examine the effect of dietary n -3 PUFA on Th1 development , DO11 .10 Rag2 - / - mice expressing transgenic T cell receptor specific for ovalbumin (OVA ) peptide were used . CD4+ T cells were isolated from spleens and lymph nodes and stimulated with ovalbumin (OVA ) peptide and irradiated BALB /c splenocytes in the presence of rIL -12 , anti -IL -4 , and rIL -2 in HMS for 2d . Cells were expanded for another 3 d in the presence of rIL -2 and rIL -12 . Dietary n -3 PUFA did not affect Th1 differentiation as assessed by the proportion of IFN -à ³+ , IL -4 - T cells in the cultures , but suppressed rIL -2 induced expansion . The suppressed expansion was due to suppressed proliferation (p <0 .05 ) . In vivo expansion of antigen -specific T cells was visualized by flow cytometric analysis of CFSE -positive transgenic T cells . Dietary n -3 PUFA did not appear to affect antigen -induced CD4+ T cell cycle progression in vivo . Overall , these results suggest dietary n -3 PUFA have no direct effect on Th2 cell development but do directly suppress Th1 cell development following both mitogenic and antigenic stimulation in vitro . |