An evaluation of the effect of eicosapentaenoic acid in the diet on macrophage PGE production and lymphocyte proliferation in a burned guinea pig model

This study was undertaken to determine if dietary eicosapentaenoic acid (EPA) could affect the production of PGE (PGE₂ and/or PGE₃) by splenic macrophages and the mitogen-induced proliferation of splenic lymphocytes.Guinea pigs received a 30% total body surface area burn following installation of gastrostomy feeding tubes. All animals received identical diets except for the lipid component which equalled 10% of total energy. The control diet contained only linoleic acid (LA) as the lipid component. The experimental diets contained increasing amounts of EPA. Fourteen days postburn, the animals were sacrificed and splenic lymphocytes and macrophages were obtained and cultured for lymphocyte proliferation with and without mitogen stimulation and for PGE₂ synthesis in response to bacterial lipopolysaccharide (LPS), respectively.Increasing amounts of EPA in the diets had no statistically significant effect on the total production of PGE (PGE₂ and/or PGE₃) by macrophages stimulated with LPS, however, when 100% EPA was used as the lipid component, the production of PGE₂ was increased. Also, increasing amounts of EPA in the diet did not affect lymphocyte proliferation following stimulation of the cells with various mitogens, although at an EPA:LA ratio of 75:25%, a significant increase in proliferation of unstimulated but not stimulated lymphocytes was observed. However, at a 100:0 ratio of EPA:LA, lymphocyte proliferation was back down to the control level. This study shows that dietary EPA in high concentrations may have some complex interaction with the immune system at least in the animal under the stress of a burn.