Proinflammatory cytokine production by mitogen-stimulated peripheral blood mononuclear cells (PBMCs) in trauma patients fed immune-enhancing enteral diets

Widespread metabolic changes associated with injury facilitate the delivery of nutrients to the immune system. The effect of specific nutrients administered by the enteral route on the immune response in trauma victims is not well understood. The purpose of this study was to examine whether the synthesis of proinflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β], and interleukin-6 [IL-6]) by peripheral blood mononuclear cells (PBMCs) are influenced by the nature of the dietary fat in critically injured trauma victims. We measured plasma TNF-α, IL-1β, and IL-6 and their release stimulated by phytohemagglutinin (PHA) and endotoxin (lipopolysaccharide, LPS) from PBMCs of 13 severely injured (injury severity score = 30 ± 2) patients once within 48–60 h after injury and then after 7 d of enteral feeding (1.5 g protein[P] · kg −1 · d −1). Group I ( n = 6) received diet A (Crucial) and group II ( n = 7) received diet B (Impact). The plasma levels of TNF-α and IL-1β in trauma patients are not significantly different from those in healthy volunteers, but plasma IL-6 levels are significantly increased (five times) in severely injured patients. Stimulation of TNF-α and IL-1β secretion by LPS and PHA were significantly higher in patients than in control subjects; in contrast, there was no stimulation of IL-6 because of trauma or nutritional support by either of the diets. Stimulation of IL-1β by LPS was normalized by Crucial but was further enhanced by Impact. The higher fat content in Crucial may contribute in part to the apparent immunomodulation. Crucial seems to be a better choice in correcting the nutritional deficiency.