Expression of two markers of germinal center T cells (SAP and PD-1) in angioimmunoblastic T-cell lymphoma

Giovanna Roncador, José Francisco García Verdes-Montenegro, Sara Tedoldi, Jennifer C. Paterson, Wolfram Klapper, Erica Ballabio, Lorena Maestre, Stefano Pileri, Martin Leo Hansmann, Miguel A. Piris, David Y. Mason, Teresa Marafioti

Research output: Contribution to journalArticlepeer-review


Background and Objectives: In the present paper we report that SAP, an intracytoplasmic molecule that is involved in cell signaling, is an immunohistologic marker for germinal center T cells in paraffin-embedded tissue. We document its expression, and also that of PD-1 (another recently described marker of germinal center T cells to which a new antibody has been raised), in normal and neoplastic lymphoid tissue to evaluate the suggestion that helper T cells within the germinal centers of human lymphoid tissue are the cell of origin of angioimmunoblastic T-cell lymphoma (AITL), and to assess the diagnostic value of these two markers. Design and Methods: Expression of SAP and PD-1 was investigated by immunohistochemistry in paraffin-embedded tissue sections and in cell lines. Western blotting was performed on cell lines, and antibody specificity was confirmed by immunostaining of transfected cells. Results: Screening on more than 500 lymphoma biopsies showed that 95% (40/42) of cases of AITL expressed at least one of these markers. SAP was also expressed on many cases (15/21) of acute T lymphoblastic leukemia, in keeping with its presence in cortical thymocytes. However, PD-1 and SAP were also found in a minority of cases of peripheral T-cell lymphoma other than AITL, in contrast to a report that the former marker is specific for AITL. This observation raises the possibility that such non-angioimmunoblastic cases may be related to germinal center helper T cells. Interpretation and Conclusions: These two markers provide additional evidence that AITL arises from germinal center T cells. They may also prove of value in the diagnosis of this disease since a negative reaction was rarely observed in this disorder.

Original languageEnglish
Pages (from-to)1059-1066
Number of pages8
Issue number8
Publication statusPublished - Aug 2007


  • AITL
  • Germinal center T cells
  • Immunohistochemistry
  • Lymphoma
  • Western blotting

ASJC Scopus subject areas

  • Hematology


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