2003 Annual Report 4.What were the most significant accomplishments this past year? D. Progress Report: This report serves to document research conducted under a trust agreement between ARS and Nestle. Additional details of research can be found in the report for the parent CRIS 1235-52000-037-00D, "The Role that Oxidatiave Stress Plays in Elevating Risk-Factor Metabolites Associated with Heart Disease." The objective of this project is to identify and measure the effect of the probiotic strain, Bifidobacterium lactis (Bb 12), as a dietary component for early induction of mucosal immune system development in newborn swine as a model for nutrient conditioning of a balanced immune system in humans. The use of probiotics as a functional food with properties that can influence both metabolic and infectious disease expression is gaining recognition by the public, but requires definition of a mechanism of action. The current research will be directed towards the use of a swine model of probiotic treatment related to application in humans. The immune system and physiology of the lung and intestines in swine closely represent that of humans. These tissue sites are targets of the effects of probiotics. Our attention is directed an early intervention strategy of feeding probiotic bacteria to pregnant sows (during the last third of pregnancy) and subsequently to their litters early in life. It is hypothesized that probiotic microbes may induce a balanced maturation of the mucosal immune system. This is similar to the strategy in humans of feeding probiotics to mothers and their newborn children, which are at risk of expression of allergic disorders, to abate the skewing of the immune system towards hyper responsiveness to allergens. Our current studies have determined the colonization pattern of Bb12 and their effect on the maturation of the intestinal immune system. After feeding animals, probiotic bacteria from fecal samples and intestinal tissues are identified using specific fluorogenic probes and real time polymerase chain reaction (PCR). Cell phenotype changes are analyzed using specific monoclonal antibodies and flow cytometry measurements; cytokine mRNA expression will be measured by real time PCR. Results from these experiments will be used to demonstrate a proof of principle for the effectiveness of probiotics on neonatal maturation and modulation of mucosal immunity.