Idiotypical Identity of IgG Myeloma Protein with Monoclonal IgM, Bence Jones Protein, and Fv Derived from One Patient

Abstract

Serum from a patient (KK) with IgG2‐λ myeloma was shown to contain multiple paraproteins corresponding to an IgM‐λ monoclonal protein (MMP), a λ‐type Bence Jones protein (BJP), and a 30 kDa component in addition to the IgG2 myeloma protein (GMP). These proteins possessed common idiotypic determinants, as judged by their monoclonal reactivity with rabbit anti‐GMP idiotype antibody (aId) in the immunofixation electrophoresis. Analysis with aId absorbed with either H or L chain of GMP revealed that the 30 kDa component shared both VH and VL with GMP and MMP. while BJP carried only the VL idiotype. The 30 kDa component, however, failed to react with antibody to either the μ, γ, α, K, or λ isotype, indicating that it had an Fv‐like molecular composition. These results suggest that myeloma cells of KK had diverged from the same precursor B cell clone to produce MPs of different isotypes and altered molecular constructions.

Studies on the Relationship between Serum Colloidal Reactions (ZTT and TTT) and IgG Subclasses, Especially IgG1 and IgG2

“…K.K. did not show the obvious decrease in IgM amount, in spite of abnormal increase in IgG, possibly because this case had also IgM -MP (5). In group two, the mobilities of MPs were shifted to /3, but cases with mobility of middle r were also observed, thus suggesting that there is no relationship between the mobility of MP and colloidal reactions.…”