Immunoglobulin genes in multiple myeloma: expressed and non-expressed repertoires, heavy and light chain pairings and somatic mutation patterns in a series of 101 cases

• Published in: Haematologica (Roma) 2006-06, Vol.91 (6), p.781-787
• Main Authors: Hadzidimitriou, A, Stamatopoulos, K, Belessi, C, Lalayianni, C, Stavroyianni, N, Smilevska, T, Hatzi, K, Laoutaris, N, Anagnostopoulos, A, Kollia, P, Fassas, A
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Bone Marrow Cells - immunology; Bone Marrow Cells - pathology; Databases, Nucleic Acid; Gene Rearrangement - immunology; Genes, Immunoglobulin; Hematologic and hematopoietic diseases; Humans; Immunodeficiencies. Immunoglobulinopathies; Immunoglobulin Heavy Chains - genetics; Immunoglobulin Light Chains - genetics; Immunoglobulinopathies; Immunopathology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Medical sciences; Multiple Myeloma - genetics; Multiple Myeloma - immunology; Mutation; Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction
• ISSN: 0390-6078; 1592-8721

Hematology Department and Hematopoietic Cell Transplantation Unit, G. Papanicolaou Hospital, Thessalonik, Greece. [e-mail] BACKGROUND AND OBJECTIVES: The available data on the immunoglobulin gene (IG) repertoire in multiple myeloma (MM) derive mainly from heavy chains; considerably less is known about light chains. We assessed in parallel IGH and IGK/IGL rearrangements in 101 MM patients so as to gain insight into: (i) IG repertoires; (ii) antigen impact; (iii) the role of receptor editing. DESIGN AND METHODS: Bone marrow aspirates were collected from all cases. IGHV-(D)-J and IGLV-J rearrangements were amplified by reverse transcriptase polymerase chain reaction (PCR). In all cases, IGKV-J rearrangements were analyzed in parallel on cDNA/genomic DNA. IGKV-KDE and IGKJ-C-INTRON-KDE were also amplified by DNA-PCR. RT-PCR products were directly sequenced. RESULTS: IGHV3 genes predominated; the IGHV4-34 gene was used in only one case. Five IGKV and five IGLV genes accounted for the majority of in-frame, transcribed IGKV-J or IGLV-J rearrangements. Taking IGKV-J, IGKV-KDE and IGKJ-C-INTRON-KDE rearrangements together, biallelic IGK locus rearrangements were detected in 22/43 k-MM cases. In l-MM, 36/42 cases had at least one rearranged IGK allele; 8/19 IGKV-J rearrangements in l-MM were in-frame. All in-frame, transcribed IGH/IGK/IGL sequences were mutated; parallel heavy/light chain analysis demonstrated a comparable impact of somatic hypermutation. INTERPRETATION AND CONCLUSIONS: Biases in IG repertoire did not seem disease-related but followed a similar pattern to that of the normal repertoire. The under-representation of the IGHV4-34 gene provides an explanation for the paucity of autoimmune phenomena in MM. Somatic mutation patterns indicate the complementary role of MM IGH/IGK/IGL sequences in antigen recognition. Finally, the frequent inactivation of productive IGKV-J joints by secondary rearrangements in MM suggests active receptor editing.