Immunoglobulin variable region gene analysis to the autoantibody-secreting B cells from tumors in association with paraneoplastic autoimmune multiorgan syndrome

Abstract

Objectives: We have studied the role of lymphoproliferative tumors in the pathogenesis of autoimmune and the origin of the autoantibodies in PNP. Objectives of this study is to understand the characteristics of immunoglobulin genes of the B-cells isolated from the tumor which can produce auto-antibody. Methods: Total RNA of the tumor cells was then isolated and the mRNA was reversely transcribed into cDNA. VH and VL genes were amplified and cloned and their sequences were analyzed. Results: 49VH genes (527 to 577 bp) and 36 VL genes (445 to 454 bp) sequences were cloned from five tumors. All of the IgVL were mostly homologous to IGKV4-01 germ-line gene. The frequency of IgVH germ-line gene usage in a decreasing order was IGHV3-23 > IGHV3-9 > IGHV4-31 > IGHV4-59. There was more nucleotide changes occurred in complementary determining regions (CDR) than those in the framework regions (FR) in the VH and VL of B cell clones. In both VH and VL, the probability (P) that the number of observed replacement mutations (R) in the CDRs would occur by random chance was low. Conclusions: The clones of B-lymphocytes in the tumors carrying possibly functional rearranged immunoglobulin heavy and light chain genes were isolated and there were high incidences of somatic mutations in CDRs and relatively conserved sequences in framework region. © 2007 The International Society of Dermatology.