SHARED N-TERMINAL SEQUENCES IN MONOCLONAL IGMK AND IGGK PROTEINS FROM A PATIENT WITH A COMPLEX MULTIPLE PARAPROTEIN DISORDER

  • 1 January 1979
    • journal article
    • research article
    • Vol. 122  (5) , 2007-2010
Abstract
The N-terminal sequence analyses were performed on the H and L chains of the idiotypically identical Ig[immunoglobulin]M.kappa. and IgG.kappa. paraproteins isolated from the serum of patient, Cam [with Waldenstrom''s macroglobulinemia]. The N-terminal 39 residues of the .kappa. chains of the IgM and IgG were identical and belonged to the human V.kappa.III subgroup. This sequenced stretch included the 1st L chain hypervariable region. The N-terminal 27 residues of the variable regions (VH) of the respective .mu. and .gamma. H chains were identical and belonged to the human VHIII subgroup. These identical VH sequences were unique with lysine residues at positions 13 and 19. The dual lysine substitution was not seen in 37 other human VHIII sequences reported in the literature. This N-terminal sequence homology in the V-regions of Cam IgM.kappa. and IgG.kappa. paraproteins and the shared idiotypy expressed by Cam IgM, IgG and IgA proteins strongly suggested the existence of complete structural homology in the variable regions of the H and L chains of these Ig molecules of 3 separate Ig classes. At the cellular and genetic level, the results point toward a common clonal origin for the idiotypically related Ig molecules and suggest that identical V-region (VH and VL) genes were utilized by the Cam lymphoid clone in the biosynthesis of the respective IgM, IgG and IgA proteins.