title: Intraclonal offspring expansion of gastric low-grade MALT-type lymphoma: evidence for the role of antigen-driven high-affinity mutation in lymphomagenesis.
abstract: Recent studies have shown that gastric mucosa-associated lymphoid tissue (MALT)-type lymphoma B cells are the malignant counterparts of hypermutated, postgerminal-center memory B cells. To further elucidate the role of antigen selection in the evolution of gastric low-grade MALT-type lymphoma, we analyzed intraclonal variations of the immunoglobulin heavy-chain variable region (Ig VH) genes expressed in three cases of lymphoma. The Ig VH genes expressed by tumor cells were amplified by PCR using primers for individual tumor-specific markers (complementarity-determining region 3 (CDR3)) and primers for six VH family leaders and then sequenced. The corresponding germ-line VH gene from these patients was also sequenced. The somatic mutations were highly concentrated in the CDR or framework region, with a clustering of replacement mutations in the CDR but only a few in the framework region. Each of the Ig VH genes of tumor cell clones of Cases 1 and 3 showed different mutations, whereas Case 2 showed no intraclonal variation. Although all three mutation pattern variants of Cases 1 and 3 occurred in postgerminal memory B cells, only one offspring from each case resulted in a dominant expansion. This finding suggests that antigen-driven high-affinity somatic mutation may play an important role in the expansion of intraclonal offspring from low-grade MALT-type lymphomas.
authors.affiliation: Virology Research Center, Institute Armand-Frappier, Laval, Québec, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Qin
authors.forename: A
authors.initials: A
authors.lastname: Greiner
authors.forename: C
authors.initials: C
authors.lastname: Hallas
authors.forename: W
authors.initials: W
authors.lastname: Haedicke
authors.forename: H K
authors.initials: HK
authors.lastname: Müller-Hermelink
mesh_terms: D001483:Base Sequence; D002999:Clone Cells; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D004273:DNA, Neoplasm / Q000032:analysis; D005803:Genes, Immunoglobulin / Q000235:genetics*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D012334:RNA, Neoplasm / Q000032:analysis; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D004273:DNA, Neoplasm; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D012334:RNA, Neoplasm