Immune components in porcine mammary secretions

Immune components present in mammary secretions are reviewed. In swine, the histological structure of the placenta prevents in utero transfer of immun oglobulins and mammary secretions are the sole source of maternal antibody for the neonate. In addition to immunoglobulins, porcine mammary secretions contain significant numbers of maternal cells of various types that may co ntribute to neonatal immunity, including phagocytes (neutrophils and macrop hages), lymphocytes (B and T cells), and epithelial cells. Immunomodulating and/or antimicrobial substances, including lactoferrin, lysozyme, lactoper oxidase, and cytokines, are also present in mammary secretions and may cont ribute to the protection of the neonate. While the role of immunoglobulins in mammary secretions is well understood, the contribution of cellular comp onents and non-specific immune factors to neonatal immunity remains to be d efined.