VH gene usage is multiple myeloma: complete absence of the VH4.21 (VH4- 34) gene

Abstract

The immunoglobin heavy chain variable region (VH) gene usage in multiple myeloma (MM) has not been reported, although a few studies have incidentally identified the VH gene rearranged in small cohorts of MM patients. We used a reverse transcriptase-polymerase chain reaction based technique to analyze the VH gene usage in MM. The VH sequences were obtained after amplification of bone marrow cDNA using the seven VH family-specific and constant region primers. The VH sequences of 72 patients were successfully identified. The frequency of VH family usage in decreasing order was VH3>VH4>VH1y>VH5>VH2>VH6>VH7 and corresponded to the functional germline complexity of the VH families. Individual VH genes (VH1–69, VH3–9, VH3–23, and VH3–30) were overrepresented in our cohort of MM patients; some VH genes [VH3–49, VH3–53, and VH4.21 (VH4- 34)], which are rearranged with increased frequency in normal circulating B cells, autoimmune diseases, and other B-cell malignancies, were not detected in any MM patient. Compared with germline sequences, an average of 8.8% (range, 2.7% to 16.5%) of the nucleotides had evidence of mutation within each VH sequence. Based on these results, we conclude that (1) the VH gene usage in MM is unique compared with other malignant and nonmalignant B-cell populations, (2) the physiologic process of clonal deletion functions to remove clones that have rearranged VH genes (VH4.21) capable of expressing antibodies, which recognize self-antigens, and (3) the complete lack of VH4.21 gene rearrangement may help to partially explain the paucity of autoimmune phenomena in MM.