Temporal changes in cytokine expression of foals during the first month of life

Foals are uniquely susceptible to a wide variety of opportunistic infections normally associated with immunodeficiencies. Little is understood about the immune system of foals during the neonatal period. An apparent age-related susceptibility predisposes neonatal foals to infectious diseases and hinders therapeutic and preventative interventions for these diseases. Cytokine expression is correlated with the type of immune response as well as the severity of a disease. In this study, we measured foal peripheral blood mononuclear cell (PBMC)-specific mRNA cytokine expression from 72 foals from three different farms during the first 4 weeks of life. Interleukin-1α (IL-1α), IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p35, IL-12p40, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and transforming growth factor-β1 (TGF-β1) were cloned and transcribed in vitro to generate antisense probes for ribonuclease protection assays. Using linear mixed-effect models, we determined that IFN-γ, TGF-β1, and IL-1α increased significantly (P<0.05) with age.