title: Different bcl-2 protein expression in high-grade B-cell lymphomas derived from lymph node or mucosa-associated lymphoid tissue.
abstract: High-grade B-cell lymphomas, whether originated in a lymph node or in mucosa-associated lymphoid tissue (MALT), show similar morphologic traits, a fact that has fueled a long-running controversy about whether they represent different entities. They differ, however, in that some high-grade MALT lymphomas show less aggressive clinical behavior, a focal low-grade component being identified in some of them. In a search for bcl-2 protein expression, we have found a significant difference between nodal (39/48) and MALT high-grade B-cell lymphoma (1/15) (P less than 0.01). Bcl-2 gene product is an inner mitochondrial membrane protein able to give a survival advantage to B-cell lines by blocking programmed cell death. This protein is usually expressed by memory or resting B cells, most activated B cells being bcl-2 negative, except in lymph-node-originated high-grade B-cell lymphomas, which appear to be mainly bcl-2 positive. Presence of bcl-2 protein in nodal large-cell lymphomas seems to be independent of a t(14;18) translocation, only being found in 19 to 28% of these lymphomas, although it constitutes a definite difference between both tumors, suggesting the existence of different molecular genetic characteristics and pathogenesis, and is possibly related to the more aggressive clinical behavior of nodal high-grade tumors.
authors.affiliation: Department of Pathology, Hospital Virgen de la Salud, Toledo, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Villuendas
authors.forename: M A
authors.initials: MA
authors.lastname: Piris
authors.forename: J L
authors.initials: JL
authors.lastname: Orradre
authors.forename: M
authors.initials: M
authors.lastname: Mollejo
authors.forename: R
authors.initials: R
authors.lastname: Rodriguez
authors.forename: M
authors.initials: M
authors.lastname: Morente
mesh_terms: D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008221:Lymphoid Tissue / Q000473:pathology*; D016393:Lymphoma, B-Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2
chemical_list: D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2