title: Inhibitory activity of alpha-1-antitrypsin bound to human IgA.
abstract: 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: D002850:Chromatography, Gel; D006801:Humans; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007070:Immunoglobulin A / Q000378:metabolism*; D009101:Multiple Myeloma / Q000097:blood; D011485:Protein Binding; D000515:alpha 1-Antitrypsin / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D007070:Immunoglobulin A; D000515:alpha 1-Antitrypsin