[1411] Differential Expression of CD317 in B-ALL, CLL and Normal B Cell Subsets

Shunyou Gong, David Kaplan, Howard Meyerson. University Hospitals of Cleveland and Case Western Reserve University School of Medicine, Cleveland, OH

Background: CD317 is a GPI-anchored surface protein traditionally recognized as a multiple myeloma antigen, and has been proved to be an effective target for multiple myeloma immunotherapies. However, the exact role of CD317 in the pathogenesis of multiple myeloma, as well as the expression profile on human hematopoietic cells, has not been well characterized. In this study, we investigated the expression of CD317 on normal B cells at various differentiation stages, and its expression in B cell precursor acute lymphoid leukemia (B-ALL) and chronic lymphoid leukemia (CLL).
Design: The blood or bone marrow specimens from 10 ALL patients, 7 CLL patients, and 13 normal individuals were stained with anti-CD317 and other lymphoid markers, and then analyzed by flow cytometry. The mean fluorescence intensity (MFI) of CD317 on malignant cells was compared with those on their normal counterparts. Over- or down-expression was evaluated by fold MFI change. Internal normal controls were used wherever possible. When internal normal counterparts were not available, MFI values from normal control samples were used to calculate fold MFI change.
Results: CD317 expression was detected on B cells at all stages of development. The expression level of CD317 increased progressively in the process of B cell maturation. CD317 expression was barely detectable in B-ALL cells (average MFI change compared to normal B cell progenitor cells: -16.8 fold). On the contrary, CD317 was consistently over-expressed in all 7 CLL patients (average MFI change: +2.1 fold).
Conclusions: CD317 is expressed throughout B cell development. In B-ALL, the expression of CD317 appears down-regulated compared to normal B cell precursors. However, similar to multiple myeloma, CD317 appears up-regulated in CLL cells. The expression of CD317 in CLL, but not B-ALL, suggests that CLL may be amenable to anti-CD317 immunotherapy.
Category: Hematopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 208, Monday Morning

 

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