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

Leonardo Flenghi, Barbara Bigerna, Marco Fizzotti, Stefania Venturi, Laura Pasqualucci, Stefano Pileri, Bihuy H. Ye, Marcello Gambacorta, Roberta Pacini, Carlo D. Baroni, Edoardo Pescarmona, Ioannis Anagnostopoulos, Harald Stein, Giampaolo Asdrubali, Massimo F. Martelli, Pier Giuseppe Pelicci, Riccardo Dalla-Favera, Brunangelo Falini

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89 Scopus citations

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 beating 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.

Original languageEnglish (US)
Pages (from-to)1543-1555
Number of pages13
JournalAmerican Journal of Pathology
Volume148
Issue number5
StatePublished - May 1 1996
Externally publishedYes

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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    Flenghi, L., Bigerna, B., Fizzotti, M., Venturi, S., Pasqualucci, L., Pileri, S., Ye, B. H., Gambacorta, M., Pacini, R., Baroni, C. D., Pescarmona, E., Anagnostopoulos, I., Stein, H., Asdrubali, G., Martelli, M. F., Pelicci, P. G., Dalla-Favera, R., & Falini, B. (1996). 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. American Journal of Pathology, 148(5), 1543-1555.