title: Immunoglobulin gene analysis reveals 2 distinct cells of origin for EBV-positive and EBV-negative Burkitt lymphomas.
abstract: The normal counterpart of the neoplastic B cells in Burkitt lymphoma (BL) is still unclear. Based on immunoglobulin gene rearrangement studies, some authors suggest an origin from germinal center cells and others from memory B cells. However, most of these studies rely on cell lines or on a small series of cases. To help clarify the cell of origin of BL, semi-nested polymerase chain reaction (PCR) was performed to amplify the VDJ rearrangements of the immunoglobulin heavy chain (V(H)) genes, and the resultant amplificates were sequenced for comparison with known germline V(H) segments. The results of this approach revealed that all cases (15 endemic BL [eBL], 10 sporadic BL [sBL], and 6 AIDS-related BL) harbor mutated V(H) genes, with different mutation ranges among the 3 types of BL. The eBL and AIDS-related forms showed considerably higher mutation rates than the sBL form (5.1%, 5.4%, and 1.5%, respectively). The mutations in eBL and AIDS-related BL also showed signs of antigen selection, whereas no signs of antigen selection were found in sBL. Finally, after subcloning the amplificates, sequence analysis revealed no signs of ongoing mutations in any of the cases analyzed. Given that one of the main differences between eBL and AIDS-related BL on the one hand and sBL on the other hand is the association with Epstein-Barr virus (EBV), we compared EBV-positive and EBV-negative BLs independently of their geographic origin and HIV status. The differences in the number of somatic mutations and antigen selection were even more evident when this approach was used. According to our molecular results, it appears that EBV-positive and EBV-negative BL may originate from 2 distinct subsets of B cells, pointing to a particular role for the germinal-center reaction in the pathogenesis of these tumors. The different types of C-MYC translocation reported in BL may also be related to the different stages of B-cell maturation.
authors.affiliation: Department of Human Pathology and Oncology, University of Siena, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Bellan
authors.forename: Stefano
authors.initials: S
authors.lastname: Lazzi
authors.forename: Michael
authors.initials: M
authors.lastname: Hummel
authors.forename: Nazzareno
authors.initials: N
authors.lastname: Palummo
authors.forename: Margherita
authors.initials: M
authors.lastname: de Santi
authors.forename: Teresa
authors.initials: T
authors.lastname: Amato
authors.forename: Joshua
authors.initials: J
authors.lastname: Nyagol
authors.forename: Elena
authors.initials: E
authors.lastname: Sabattini
authors.forename: Thierry
authors.initials: T
authors.lastname: Lazure
authors.forename: Stefano A
authors.initials: SA
authors.lastname: Pileri
authors.forename: Martine
authors.initials: M
authors.lastname: Raphael
authors.forename: Harald
authors.initials: H
authors.lastname: Stein
authors.forename: Piero
authors.initials: P
authors.lastname: Tosi
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Leoncini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001402:B-Lymphocytes / Q000473:pathology; D002051:Burkitt Lymphoma / Q000235:genetics / Q000473:pathology* / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin; D018858:Germinal Center / Q000473:pathology; D004854:Herpesvirus 4, Human; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D016483:Lymphoma, AIDS-Related / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D007143:Immunoglobulin Heavy Chains