Isolation and Characterization of The Basic, Diagnostic IgG Globulin in the Rare Gammopathy, Papular Mucinosis

Abstract

Abstract A homogeneous, basic immunoglobulin has been isolated from the serum of a patient with the rare gammopathy, papular mucinosis. Comparative amino acid analysis of the diagnostic protein (PM protein) and of the more basic, normal IgG fractions indicates that the unusually high basicity of the PM protein cannot be ascribed to an increase in the content of the basic amino acids. However, it has been found that the basicity of the PM protein is associated with the Fab portion of the molecule. The PM protein is a papainsensitive IgG1 globulin, and it has only type lambda light chains which is characteristic of all known PM proteins. The PM protein was found to be immunologically identical to normal IgG with the use of antisera directed to IgG1 globulins and lambda light chains.