title: Monoclonal antibodies PG-B6a and PG-B6p recognize, respectively, a highly conserved and a formol-resistant epitope on the human BCL-6 protein amino-terminal region.
abstract: The human BCL-6 gene, which is rearranged in approximately 30% of diffuse large B cell lymphomas, encodes a 706-amino-acid nuclear protein of the Kruppel-type zinc finger transcription factors mainly expressed in normal germinal center B cells and related lymphomas. Four monoclonal antibodies (PG-B6, PG-B6a, PG-B6p, and PG-B6m), specifically directed against the human BCL-6 protein, were generated by immunizing BALB/c mice with a recombinant protein corresponding to the BCL-6 amino-terminal region (amino acids 3 to 484). The PG-B6 monoclonal antibody reacted with a BCL-6 epitope sensitive to fixatives and preserved in all mammalian species. PG-B6a (a is for avian) recognized the most evolutionarily conserved BCL-6 epitope (expressed in all animal species including avian). PG-B6p (p is for paraffin) recognized a fixative-resistant epitope of BCL-6 that was detectable on paraffin sections after microwave heating in 1 mmol/L EDTA buffer. PG-B6m (m is for mantle) was the least specific monoclonal antibody as, in addition to BCL-6, it reacted with a yet undefined antigen selectively located in the cytoplasm of mantle and marginal zone B cells. All monoclonal antibodies detected strong nuclear expression of BCL-6 in follicular lymphomas, diffuse large B cell lymphomas, Burkitt's lymphomas, and nodular, lymphocyte-predominance Hodgkin's disease. In diffuse large B cell lymphomas, BCL-6 expression was independent of BCL-6 gene rearrangements and did not correlate with expression of other markers or the proliferation index. BCL-6 was not expressed in B-CLL, hairy cell leukemia, mantle-cell- and marginal-zone-derived lymphomas. Labeling of paraffin sections with PG-B6p proved useful for differentiating proliferation centers in B-CLL (BCl-2+/BCL-6-) from trapped germinal centers in mantle cell lymphomas (BCL-2-/BCL-6+) and for identifying neoplastic cells in cases of nodular, lymphocyte-predominance Hodgkin's disease. Because of their high specificity, wide reactivity in humans and animal species including avians (PG-B6a), and suitability for labeling routine paraffin sections (PG-B6p), the reagents described in this paper should prove valuable in both research and diagnostics.
authors.affiliation: Institute of Hematology, University of Perugia, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Flenghi
authors.forename: B
authors.initials: B
authors.lastname: Bigerna
authors.forename: M
authors.initials: M
authors.lastname: Fizzotti
authors.forename: S
authors.initials: S
authors.lastname: Venturi
authors.forename: L
authors.initials: L
authors.lastname: Pasqualucci
authors.forename: S
authors.initials: S
authors.lastname: Pileri
authors.forename: B H
authors.initials: BH
authors.lastname: Ye
authors.forename: M
authors.initials: M
authors.lastname: Gambacorta
authors.forename: R
authors.initials: R
authors.lastname: Pacini
authors.forename: C D
authors.initials: CD
authors.lastname: Baroni
authors.forename: E
authors.initials: E
authors.lastname: Pescarmona
authors.forename: I
authors.initials: I
authors.lastname: Anagnostopoulos
authors.forename: H
authors.initials: H
authors.lastname: Stein
authors.forename: G
authors.initials: G
authors.lastname: Asdrubali
authors.forename: M F
authors.initials: MF
authors.lastname: Martelli
authors.forename: P G
authors.initials: PG
authors.lastname: Pelicci
authors.forename: R
authors.initials: R
authors.lastname: Dalla-Favera
authors.forename: B
authors.initials: B
authors.lastname: Falini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D002417:Cattle; D002645:Chickens; D010856:Columbidae; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000032:analysis* / Q000276:immunology; D006801:Humans; D007158:Immunologic Techniques; D008221:Lymphoid Tissue / Q000737:chemistry / Q000378:metabolism / Q000473:pathology; D008223:Lymphoma / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D014066:Palatine Tonsil / Q000737:chemistry / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D051560:Proto-Oncogene Proteins c-bcl-6; D011817:Rabbits; D051381:Rats; D012756:Sheep; D013045:Species Specificity; D013154:Spleen / Q000737:chemistry / Q000473:pathology; D013552:Swine; D014157:Transcription Factors / Q000032:analysis* / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D004268:DNA-Binding Proteins; D000939:Epitopes; D011518:Proto-Oncogene Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D014157:Transcription Factors