Transcription factor B-cell-specific activator protein (BSAP) is differentially expressed in B cells and in subsets of B-cell lymphomas

Laszlo Krenacs, Andreas W. Himmelmann, Leticia Quintanilla-Martinez, Thierry Fest, Agostino Riva, Axel Wellmann, Eniko Bagdi, John H. Kehrl, Elaine S. Jaffe, Mark Raffeld

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The paired box containing gene PAX-5 encodes the transcription factor BSAP (B-cell-specific activator protein), which plays a key role in B- lymphocyte development. Despite its known involvement in a rare subtype of non-Hodgkin's lymphoma (NHL), a detailed examination of BSAP expression in NHL has not been previously reported. In this study, we analyzed normal and malignant lymphoid tissues and cell lines, including 102 cases of β-cell NHL, 23 cases of T- and null-cell NHL, and 18 cases of Hodgkin's disease. Normal lymphoid tissues showed strong nuclear BSAP expression in mantle zone B cells, less intense reactivity in follicular center B cells, and no expression in cells of the T-cell-rich zones. Monocytoid B cells showed weak expression, whereas plasma cells and extrafollicular large transformed B cells were negative. Of the 102 B-cell NHLs, 83 (81%) demonstrated BSAP expression. All of the 13 (100%) B-cell chronic lymphocytic leukemias (B- CLLs), 21 of (100%) mantle cells (MCLs), and 20 of 21 (95%) follicular lymphomas (FLs) were positive. Moderate staining intensities were found in most B-CLL and FL cases, whereas most MCLs showed strong reactions, paralleling the strong reactivity of nonmalignant mantle cells. Eight of 12 (67%) marginal zone lymphoma cases showed negative or low BSAP levels, and 17 of 24 (71%) large B-cell lymphomas displayed moderate to strong expression. None of the 23 T- and null-cell lymphomas reacted with the BSAP antisera, whereas in Hodgkin's disease, 2 of 4 (50%) nodular lymphocytic predominance and 5 of 14 (36%) classical cases showed weak nuclear or nucleolar BSAP reactions in a fraction of the tumor cells. Western blot analysis showed a 52-kD BSAP band in B-cell lines, but not in non-B-cell or plasma cell lines. We conclude that BSAP expression is largely restricted to lymphomas of B- cell lineage and that BSAP expression varies in B-cell subsets and subtypes of B-cell NHL. The high levels of BSAP, especially those found in large-cell lymphomas and in some follicular lymphomas, may be a consequence of deregulated gene expression and suggest a possible involvement of PAX-5 in certain B-cell malignancies.

Original languageEnglish
Pages (from-to)1308-1316
Number of pages9
Issue number4
Publication statusPublished - Aug 15 1998


ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

Cite this

Krenacs, L., Himmelmann, A. W., Quintanilla-Martinez, L., Fest, T., Riva, A., Wellmann, A., Bagdi, E., Kehrl, J. H., Jaffe, E. S., & Raffeld, M. (1998). Transcription factor B-cell-specific activator protein (BSAP) is differentially expressed in B cells and in subsets of B-cell lymphomas. Blood, 92(4), 1308-1316.