Inhibitory activity of alpha-1-antitrypsin bound to human IgA

Clin Chim Acta. 1978 Apr 3;85(1):61-6. doi: 10.1016/0009-8981(78)90101-8.


Complexes between alpha-1-antitrypsin (alpha 1AT) and monoclonal IgA are regularly demonstrable in the plasma of myeloma patients. These alpha 1AT-IgA complexes, free of contamination by unbound alpha 1AT, are purified from 5 myeloma patients sera using salt-mediated hydrophobic chromatography. The complexes have a molecular weight greater than or equal to 400 000: this suggests that alpha 1AT is bound to di- or polymeric IgA. The alpha 1AT bound to IgA constitutes the 3.2, 3.5, 7.2, 8.5, and 24.6 per cent of the total alpha 1AT present in the 5 myeloma serum samples. There is a linear correlation between bound alpha 1AT concentration and IgA level in the range of the IgA concentrations considered (r = 0.988; p less than 0.05). Similar values are obtained quantitating bound alpha 1AT by radioimmunodiffusion technique or by determination of the trypsin-inhibiting capacity; this demonstrates that the bound alpha 1AT fully retains its inhibitory capacity. The biological significant of this binding phenomenon is discussed.

MeSH terms

  • Chromatography, Gel
  • Humans
  • Immunodiffusion
  • Immunoelectrophoresis
  • Immunoglobulin A / metabolism*
  • Multiple Myeloma / blood
  • Protein Binding
  • alpha 1-Antitrypsin / metabolism
  • alpha 1-Antitrypsin / pharmacology*


  • Immunoglobulin A
  • alpha 1-Antitrypsin