Impact of diet on development of bronchial-associated immunity in the neonatal piglet

► The effect of early nutrition (mothers milk vs. formula) and development (d7 vs. d21) on lymphocyte populations and gene expression was studied in piglets. ► Developmental effects were observed in lymphocyte populations in blood, mediastinal and thoracic lymph nodes. ► Lymphocyte populations in mediastinal and thoracic lymph nodes were also affected by diet. ► Developmental and dietary effects were observed in cytokine expression in lung, mediastinal and thoracic lymph nodes. Bronchial-associated immune development is critically important to protect neonates from respiratory infections. Herein, bronchial-associated immune development in formula-fed and sow-reared pigs is described. Colostrum-fed newborn piglets were fed medicated sow milk replacer formula beginning at 48h of life or remained with the sow. Blood and tissues were sampled at one-week (d7) and three-weeks (d21) of age. Lymphocyte subpopulations, including T helper 2, cytotoxic T, memory T, and NK cells, in peripheral blood, mediastinal lymph nodes, and thoracic lymph nodes were identified using flow cytometry. Additionally, IL-1β, IL-6, IL-12, TNFα, TGF-β1, TGF-β2, IFNα, IFNβ, and dectin gene expression were analyzed by quantitative RT-PCR. Total IgG, IgM, and IgA concentrations in serum were analyzed. Dietary and developmental effects were observed. This set of baseline measurements provides a framework for future respiratory challenge studies where the effects of diet on the neonate's ability to resist and/or recover from infection can be tested.