J chain synthesis and secretion of hexameric IgM is differentially regulated by lipopolysaccharide and interleukin 5

Academic Article

Abstract

  • Two functional polymeric forms of IgM can be produced by antibody-secreting B cells. Hexameric IgM lacks detectable J (joining) chain and activates complement 17-fold better than pentameric IgM, which usually contains one J chain per pentamer. Using the inducible B-cell lymphoma CH12, we determined if the synthesis of a particular polymeric form of IgM is a fixed property of B cells or can be altered. Lipopolysaccharide (LPS)-stimulated CH12 cells produced mixtures of IgM hexamers and pentamers, resulting in antibody with high complement-fixing activity. In contrast, interleukin-5-stimulated CH12 cells secreted predominately pentameric IgM, with a correspondingly lower lytic activity. Differences in lytic activity were due only to the amount of hexameric IgM in the secreted antibody. Interleukin 5 stimulated higher production of J chain RNA and protein than LPS, while LPS induced the highest levels of the secretory form of μ protein. The amount of hexameric IgM secreted was therefore inversely proportional to the level of intracellular J chain protein in the responding B cells. We conclude that the biologic function of IgM produced by B cells differs depending on how they are stimulated and that this difference may be regulated by the relative availabilities of J chain and secretory μ proteins during IgM polymerization.
  • Digital Object Identifier (doi)

    Pubmed Id

  • 2162150
  • Author List

  • Randall TD; Parkhouse RME; Corley RB
  • Start Page

  • 962
  • End Page

  • 966
  • Volume

  • 89
  • Issue

  • 3