013 (CD99) positivity in hematologic proliferations correlates with TdT positivity

Area of Science:

• Immunology
• Hematopathology
• Oncology

Background:

• The monoclonal antibody 013 identifies the CD99 glycoprotein, a marker for neuroepithelioma and Ewing's sarcoma.
• 013 is also found on immature T cells and hematopoietic precursors, showing reactivity in various hematologic malignancies.
• The distribution of 013 positivity resembles that of terminal deoxynucleotidyl transferase (TdT), prompting investigation into their correlation.

Purpose of the Study:

• To investigate the correlation between 013 antibody reactivity and TdT positivity in a spectrum of hematologic malignancies.
• To evaluate the potential of 013 as an additional diagnostic marker for TdT-positive leukemias and lymphomas.

Main Methods:

• Utilized heat-induced epitope retrieval and automated immunostaining techniques.
• Compared the reactivity of monoclonal antibody 013 with TdT in 67 lymphoblastic lymphomas/leukemias, 6 chronic myelogenous leukemias in blast crisis, various acute myeloid leukemias, 5 granulocytic sarcomas, and 94 diffuse lymphomas.
• Analyzed the co-expression patterns of 013 and TdT in conventionally processed tissue sections.

Main Results:

• All 013-positive cases demonstrated TdT positivity.
• 013 reacted with 71% of TdT-positive lymphoblastic lymphomas and acute lymphoblastic leukemias.
• 013 was also positive in TdT-positive acute myeloid leukemia, chronic myelogenous leukemia in blast crisis, and granulocytic sarcomas, but negative in TdT-negative leukemias and other lymphomas.

Conclusions:

• 013 positivity appears restricted to hematologic proliferations that are also TdT positive.
• The monoclonal antibody 013 may serve as a valuable adjunct marker for diagnosing TdT-positive leukemias and lymphomas in tissue sections.