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Abstract
Effect of age and cortisol on equine dendritic cells after exposure to bacteria ex vivo.Gorham B, Hurley D, Gigure S, Norton N, Giancola S, Hart K. Dendritic cells (DCs) are important in the immune response to bacteria, but foal DC function is not well characterized. Monocyte-derived DCs (MoDCs) were generated from 8 foals at 1, 7 and 30 days-of-age and 9 adult horses. MoDCs were incubated for 48 hours with or without killed Escherichia coli or Staphlococcous aureus antigen in the presence or absence of cortisol (15 g/dl). MoDC expression of MHCII, CD86, and CD14 was measured with flow cytometry, and supernatant cytokine concentrations (IL-4, IL-17, IFN-gamma, IFN-alpha, and IL-10) were quantified with a fluorescent bead-based immunoassay. Effects of age and cortisol on MoDC variables were determined with mixed-effects linear models (significance P < 0.05). The percentage of cells expressing MHCII and CD86 was lower and CD14 was higher in 1-day-old-foal MoDCs compared to horse MoDCs (P < 0.006). Bacterial exposure alone did not alter surface marker expression in foal or horse cells, but exposure to bacteria with cortisol further reduced MHCII expression in foal cells (P < 0.001). Following bacterial exposure, 1-day-old-foal MoDCs produced significantly less IL-4, IL-17, IFN-gamma, and IFN-alpha and more IL-10 than horse MoDCs (P < 0.001). Foal MoDCs exhibit phenotypic and functional immaturity that persists during the first month of life and is compounded by exposure to cortisol. Thus, foal DCs may be less effective at activating lymphocyte responses, which could contribute to foals increased susceptibility to bacterial sepsis.