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It has been suggested that VH4-34 gene segment expression is counter-selected in multiple myeloma (MM) due to a self-tolerance mechanism. We cloned and sequenced a VH4-34 gene segment from bone marrow mononuclear cells of a stage III MM patient. We show that VH4-34 was expressed by the serum IgA myeloma (M)-protein, as demonstrated by reactivity with the VH4-34 specific 9G4 mAb and mass spectrometry (MS). The M-protein had weak reactivity with nuclei. These results demonstrate that VH4-34 may be expressed in secreted IgA M-protein with weak autoreactivity. Thus, counter-selection of VH4-34 is pronounced but not absolute in MM. Mechanisms of how VH4-34 can occasionally be expressed in MM and clinical implications are discussed.

Multiple myeloma (MM) remains a difficult-to-cure cancer and less than 20% of patients achieve long-term survival irrespective of the treatment delivered, including high-dose chemotherapy. Thus, new treatment modalities are urgently needed. Myeloma cells produce a monoclonal immunoglobulin (Ig) which is a truly tumor-specific antigen. The tumor-specific antigenic determinants are localized in the variable regions of the monoclonal Ig and are termed idiotopes (Id). Id-vaccination, i.e., vaccination with the autologous monoclonal Ig, has been performed in MM patients in order to elicit tumor-specific immune responses and possibly elimination of myeloma cells. However, clinical trials have not given the promising results obtained in mice. This review focuses on tolerance mechanisms that might hinder Id-specific immune responses in MM patients. New strategies for Id vaccination in MM are discussed.