Docosahexaenoic acid (DHA) was obtained from Cayman Chemical (Ann Harbor, MI), RPMI and DMEM media and fetal bovine serum (FBS) from Invitrogen (Carlsbad, CA), and mouse interleukin 4 (IL-4) from Sigma Chemical (St Louis, MO, USA). Coelenterazine was purchased from MedChem Express (Monmouth Junction, NJ). Mouse diets were purchased from DYETS, Inc. (Bethlehem, PA). For the ω-6 diet, 30% of energy (134 g/kg) was provided by corn oil, and the ω-6 to ω-3 ratio was 18:1. For the ω-3 diet 30% of energy was provided by menhaden oil (134 g/kg) and the ω-6 to ω-3 ratio was 1:8 as previously described [5 (link)].