Expression of Lymphoid-Specific Helicase in Reactive Lymph Nodes and B-Cell Lymphomas
AS Duffield, AM Schneider, R Sharma, MJ Borowitz, D Small, KH Burns. Johns Hopkins University School of Medicine, Baltimore, MD
Background: Helicase, lymphoid-specific (HELLS or LSH) is a member of the SNF2 family of helicases, and regulates transcription, heterochromatin formation, and transposon silencing through cooperation with DNA methyltrasferases. Previous research has shown that HELLS is highly expressed in lymphoid precursor cells. Although the loss or dysregulation of HELLS has been implicated in human and animal models of malignancy, to our knowledge HELLS protein expression has not been reported in benign human tissues or explored as a marker in anatomic pathology.
Design: In order to determine whether HELLS is involved in B-cell development or lymphomagenesis, we performed immunohistochemical studies with an antibody directed against HELLS on benign reactive lymph nodes and a tissue microarray containing a collection of B-cell lymphomas.
Results: We found that in reactive lymph nodes, expression of HELLS is largely restricted to the dark zone of germinal centers. The B-cell lymphoma microarray included B-lymphoblastic (3 cases), Burkitt (3), diffuse large B-cell (10), classical Hodgkin (4), follicular (12), mantle (4), marginal zone (7) and small lymphocytic (6) lymphomas. We found that the Burkitt lymphomas and a subset of diffuse large B cell lymphomas express HELLS in a significant number of the tumor cells consistent with its association with germinal centers. Unexpectedly, most follicular lymphomas did not express HELLS, and this lack of reactivity facilitated the distinction between the reactive and neoplastic follicles. Other low grade B-cell lymphomas, including small lymphocytic, mantle and marginal zone lymphomas expressed HELLS in only rare cells. We also found that HELLS was expressed in many of the Reed-Sternberg (RS) cells in classical Hodgkin lymphoma but not in the background lymphocytes, allowing for relatively straightforward identification of the RS cells in these specimens.
Conclusions: These findings suggest that HELLS expression could provide a new diagnostic marker for selected lymphomas, and that this protein may play an important role in both germinal center B-cell development and lymphomagenesis.
Monday, March 22, 2010 1:00 PM
Poster Session II # 165, Monday Afternoon