A specific monoclonal antibody (PG-B6) detects expression of the BCL-6 protein in germinal center B cells

L. Flenghi, B. H. Ye, M. Fizzotti, B. Bigerna, G. Cattoretti, S. Venturi, R. Pacini, S. Pileri, F. Lo Coco, E. Pescarmona, P. G. Pelicci, R. Dalla-Favera, B. Falini

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Abstract

The BCL-6 gene is frequently involved in translocations occurring at the 3q27 locus and is rearranged in approximately 30% of diffuse large cell lymphomas and in a small fraction of follicular lymphomas. The BCL-6 gene encodes for a Kruppel-type zinc-finger protein, the cell/tissue expression and function of which is unknown. In this study, we describe a new monoclonal antibody (PG-B6) that is specifically directed against a fixative-sensitive epitope on the amino-terminal region of the BCL-6 protein. By immunocytochemical analysis, BCL-6 localizes in the nucleus where PG-B6 staining gives a microgranular/diffuse pattern with exclusion of the nucleoli. The main reactivity of PG-B6 in tonsil and spleen is with the nuclei of germinal center B cells, whereas B cells within the mantle and marginal zones do not express BCL-6. No other lymphoid cells in the tonsil express BCL-6 except for a subset of CD3+/CD4+ intrafollicular and interfollicular T cells. A few lymphoid cells of unknown phenotype express BCL-6 in the thymus. Extra-lymphoid BCL-6 expression includes a weak nuclear positivity of epithelia. In non-Hodgkin's lymphomas, BCL-6 expression parallels that observed in normal lymphoid compartments, eg, expression in germinalcenter-derived tumors (follicular and diffuse large cell lymphomas), but not in mantle cell and marginal zone lymphomas. In most diffuse large cell lymphomas, the BCL-6 protein is expressed at high levels in cases with or without BCL-6 gene rearrangements. These findings indicate that BCL-6 expression is specifically regulated during B lymphocyte development and suggest that BCL-6 may play a role during B cell differentiation in the germinal center.

Original languageEnglish (US)
Pages (from-to)405-411
Number of pages7
JournalAmerican Journal of Pathology
Volume147
Issue number2
Publication statusPublished - Jan 1 1995
Externally publishedYes

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ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Flenghi, L., Ye, B. H., Fizzotti, M., Bigerna, B., Cattoretti, G., Venturi, S., ... Falini, B. (1995). A specific monoclonal antibody (PG-B6) detects expression of the BCL-6 protein in germinal center B cells. American Journal of Pathology, 147(2), 405-411.