title: Alpha-chain disease: analysis of alpha-chain protein and secretory component in jejunal fluid.
abstract: BACKGROUND
  It is unclear why different forms of alpha-chain disease protein appear in intestinal fluid. This was studied in a 23-year-old Mauritanian man in whom alpha-chain disease was diagnosed localized to the duodenum and jejunum, nasopharynx, and bone marrow.
  
  
  METHODS
  The duodenal infiltrate was studied by immunohistochemistry. Forms of alpha chain-containing proteins in serum and jejunal fluid were analyzed by ultracentrifugation and radioimmunoassays.
  
  
  RESULTS
  The infiltrating cells contained alpha-1 chain but no light chains, and approximately 66% showed variable expression of J chain. Serum contained a large fraction of monomeric alpha-chain disease protein, whereas both monomeric and heavier forms appeared in jejunal fluid. Some of the latter were bound to secretory component, and the fluid contained virtually no free component.
  
  
  CONCLUSIONS
  Linkage of polymeric alpha-chain disease protein to secretory component depends on balanced synthesis of alpha chains and J chain in the proliferating B cells, giving rise to polymers with binding site for secretory component expressed as an epithelial receptor. Insufficient receptor-mediated transport capacity (either relative and/or because of intestinal crypt reduction) results in passive external transfer of polymers without bound secretory component along with leakage of serum-derived or locally produced monomeric alpha-chain disease protein, the latter presumably originating from immunocytes with little or no J-chain synthesis.
authors.affiliation: Laboratoire d'Explorations Fonctionelles Digestives, Centre Hospitalier Regional Universitaire, Lille, France.
authors.forename: D
authors.initials: D
authors.lastname: Lucidarme
authors.forename: J F
authors.initials: JF
authors.lastname: Colombel
authors.forename: P
authors.initials: P
authors.lastname: Brandtzaeg
authors.forename: M
authors.initials: M
authors.lastname: Tulliez
authors.forename: S
authors.initials: S
authors.lastname: Chaussade
authors.forename: P
authors.initials: P
authors.lastname: Marteau
authors.forename: J P
authors.initials: JP
authors.lastname: Dehennin
authors.forename: J P
authors.initials: JP
authors.lastname: Vaerman
authors.forename: J C
authors.initials: JC
authors.lastname: Rambaud
mesh_terms: D000328:Adult; D001826:Body Fluids / Q000737:chemistry*; D002499:Centrifugation, Density Gradient; D006801:Humans; D007137:Immunoglobulin alpha-Chains / Q000032:analysis* / Q000097:blood; D007150:Immunohistochemistry; D007161:Immunoproliferative Small Intestinal Disease / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism*; D008297:Male; D012635:Secretory Component / Q000032:analysis*; D014461:Ultracentrifugation
chemical_list: D007137:Immunoglobulin alpha-Chains; D012635:Secretory Component