3 MONOCLONAL IMMUNOGLOBULINS, AN IGG2(K), AN IGM(K) AND AN IGM-A HYBRID, IN ONE PATIENT .2. SHARING OF COMMON VARIABLE REGIONS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 44  (2) , 265-271
Abstract
Amino acid sequencing and hemagglutination inhibition studies were performed on 3 monoclonal Ig (an IgG2, an IgM and an IgM/A hybrid) isolated from a patient afflicted with a multiple gammopathy. All 3 proteins have shared idiotypic determinant(s). The L chains of all 3 paraproteins have identical NH2-terminal amino-acid sequences at all positions determined thus far. The NH2-terminal amino-acid sequence of the .gamma. chains is identical to that of the .mu. chain. The evidence strongly suggests a common ancestral clonal origin for cells which produce these paraproteins and that identical variable region (VH [H chain variable region] and VL [L chain variable region]) genes were used by the patient''s lymphocyte subclones in the biosynthesis of the respective IgM, IgG and IgM/A hybrid molecules. The occurrence of a .mu./.alpha. hybrid chain, which shares identical V regions with a .mu. and a .gamma. chain, is consistent with the concept that IgM-producing cells can develop directly into cells producing other classes of Ig via separate pathways during B cell maturation.