Measurement of IgG-α1 anti-trypsin (α1AT) complex in the sera of patients with IgA myelomatosis

Abstract The level of IgA- α 1 anti-trypsin ( α 1 AT) complex in a relatively large number of IgA myeloma sera has been determined, and compared with their content of polymerised forms of IgA. The level of the complex was the same in sera containing only monomeric IgA, some polymer and more than 50% polymer (as determined by SDS-PAGE). There was, however, a highly significant inverse correlation between the amount of IgA- α 1 AT complex in the myeloma sera and their content of 10S dimer (as determined by analytical ultracentrifugation). High levels of IgA- α 1 AT complex were also found in the small number of myeloma sera examined which contained paraprotein of the minor allotypic form of (Am 2+ ) of the IgA 2 sub-class, indicating that the lack of disulphide bonds between the heavy and light chains of this isotype has no influence on its ability to complex with α 1 AT.