Establishment and characterization of a new human myeloma cell line, KYδ-1, producing the δ/κ type immunoglobulin

We describe the establishment and characterization of a new multiple myeloma (MM) cell line, KYδ-1, which expressed δ/κ type immunoglobulin (Ig). The patient was a 65-year-old woman with MM, who presented extramedullary dissemination, lymphadenopathy and short survival. The KYδ-1 cell line was derived from the pleural fluid obtained in the terminal phase of the disease. The cells expressed δ/κ Ig in the cytoplasm, and CD10, CD29, CD33, CD38, CD44, CD54, and HLA-DR antigens on the cell surface. Chromosomal analysis revealed two independent translocations, t(3;14)(p21;q32) and t(3;11)(p21;q13), which were confirmed by fluorescence in situ hybridization using chromosome painting probes. Reverse transcriptase-mediated polymerase chain reaction (PCR) and Northern blot analyses demonstrated overexpression of the CCND1 gene, suggesting alteration of the BCL1-CCND1 locus. We thus performed long-distance inverse PCR using nested primers for the Cα constant region of immunoglobulin heavy chain gene (IGH) and obtained a clone that encompassed the 11q13/IGH fusion. Nucleotide sequencing determined that the fusion occurred at the Sα2 switch region and at the centromeric side of the major translocation cluster of BCL1. The other IGH allele consisted of a VDJ complex that was adjacent to the Cδ constant gene, indicating that a class switch-like mechanism from the Cμ to Cδ was involved in the production of the Ig δ heavy chain. Point mutations within the P53 and N-RAS genes were presumably related to the rapidly progressive disease in this particular MM patient.