title: Dietary fish oil impairs primary host resistance against Listeria monocytogenes more than the immunological memory response.
abstract: The primary objective of this study was to determine whether dietary (n-3) polyunsaturated fatty acids (PUFA) impair the ability of mice to generate an immunological memory response against the bacterial pathogen, Listeria monocytogenes. Weanling BALB/c female mice were fed for 28 d one of two semipurified high fat diets containing either lard or refined menhaden fish oil, rich in long-chain (n-3) PUFA. Mice were immunized with 10(4) or 10(3) colony forming units (cfu) bacteria. Thirty-five days later, these immune mice and age-matched naïve (i.e., unimmunized) mice were challenged with 10(5) cfu bacteria. Three days postchallenge, bacterial clearance was determined. Compared with lard-fed mice, naïve mice in the fish oil treatment group had higher bacterial loads in their liver and spleen (P < 0.001). When mice were immunized with 10(4) cfu bacteria before rechallenge with 10-fold more bacteria, both lard- and fish oil-fed mice had significantly lower bacterial loads in their liver and spleen (e.g., approximately 2 log(10); P < 0.001) compared with their naïve counterparts. However, when the immunization dose was reduced to 10(3) bacteria, a modest diet treatment effect was observed, such that compared with immune lard-fed mice, immune fish oil-fed mice had significantly greater bacterial loads in their liver and spleen (i.e., approximately 0.5 log(10); P < 0.01). These data demonstrate for the first time that although dietary (n-3) PUFA can significantly impair host resistance to a primary as well as a secondary L. monocytogenes infection, the impairment of the immunological memory response is much less severe.
authors.affiliation: Nutritional Sciences Graduate Program, University of Missouri, Columbia 65211, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Irons
authors.forename: Michele J
authors.initials: MJ
authors.lastname: Anderson
authors.forename: Meijuan
authors.initials: M
authors.lastname: Zhang
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Fritsche
mesh_terms: D000818:Animals; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage*; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage*; D007156:Immunologic Memory; D008089:Listeria monocytogenes / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D004042:Dietary Fats, Unsaturated; D005395:Fish Oils