Immunoglobulin V region heavy and light chain gene sequences of the lymphoblastoid cell line GM 4672

Abstract

GM 4672 is an IgG2 kappa-producing lymphoblastoid cell line derived from a patient with multiple myeloma. It has been used by many laboratories as a fusion partner for the production of human-human hybridoma monoclonal antibodies. GM 4672 immunoglobulin variable region heavy and light chain family usage was originally assigned to VH1 and VK1, respectively. This assignment was based on the positions of [3H]leucine of the heavy and light chain proteins using the Edman degradation method. Using the polymerase chain reaction and variable region leader primers and constant region primers, we report here the immunoglobulin variable region gene sequence expressed by GM 4672. The VH region belongs to the VH4 family and is most homologous with the V71-2 (87.9%), DK1, and JH4 germline genes. The entire heavy chain V region contained 41 mutations in 36 codons and included 11 N nucleotide additions flanking the D region. GM 4672 VK region contained a VK1 gene rearranged with a JK4 gene. The VK germline gene used by GM 4672 light chain was not identified but showed the most homology with Vb' germline gene (87.7%). When compared to Vb' and JK4 genes, there were 37 mutations in 30 codons with evidence of antigen selection as determined by the replacement to silent mutation ratio in the complementarity-determining regions. The high frequency of mutations in the V region genes of GM 4672 is comparable to the sequences of other myeloma proteins.