CHARACTERIZATION AND LOCALIZATION OF SECRETORY COMPONENT IN CHICKEN

  • 1 January 1978
    • journal article
    • research article
    • Vol. 34  (3) , 471-478
Abstract
A component found free in intestinal contents and cecal contents of conventional and germ-free chickens (lacking Ig[immunoglobulin]A producing cells) had similar characteristics to mammalian secretory component (SC). Free secretory component (FSC) showed a classic reaction of partial identity with secretory (s) IgA from bile, intestinal contents and cystic oviduct fluid. There was demonstrable cross-reactivity between FSC and a low MW component released from SIgA by mild reductive dissociation, confirming the presence of a disulfide-linked accessory polypeptide chain. Fractionation of serum IgA revealed 2 molecular classes of IgA, a high MW 15S IgA which possessed SC and could not be differentiated antigenically from SIgA and a low MW 7S IgA which showed a reaction of partial identity with 15S IgA and non-identity with FSC. Fluorescent localization of SC in young germ-free chicks demonstrated its presence in the supranuclear golgi zone, apical cytoplasm and basement membrane of crypt epithelial cells. The characteristics of chicken SIgA are closely aligned with those of its mammalian counterpart. There apparently is a system in which SIgA is the synthetic product of 2 distinct cells, with final assembly occurring in the crypt epithelium.