[1517] Flow Cytometric Assessment of CD200 (OX-2 Membrane Glycoprotein) Expression in B Cell Lymphoproliferative Disorders

Vinodh Pillai, Olga Pozdnyakova, Karry Charest, Betty Li, David M Dorfman. Brigham and Women's Hospital, Boston, MA

Background: CD200 (OX-2 antigen), a type I Ig superfamily membrane glycoprotein expressed in B cells, a subset of T cells, and other cell types, interacts with CD200R, an inhibitory receptor expressed on myeloid/monocyte lineage cells, and has a suppressive effect on T cell mediated immune response, including suppression of the anti-tumor immune response when CD200 is expressed by neoplastic cells. CD200 is expressed by neoplastic cells in multiple myeloma, AML, and in a number of carcinomas and other neoplasms. CD200 was found to be expressed in CLL/SLL and hairy cell leukemia. Recently we found by immunohistochemical staining that CD200 is expressed in a number of additional B cell neoplasms.
Design: We studied the expression of CD200 in 121 recent specimens from a range of B cell lymphoproliferative disorders, to determine its utility as a flow cytometric marker for the characterization of these diseases. Six-color flow cytometric immunophenotypic analysis was performed using a FACSCanto II flow cytometer, with concurrent assessment of CD19, CD20, CD5, CD10, CD23, and other markers using FACSDiva software.
Results: For B cell lymphoproliferative disorders in which at least 10 clinical cases were available for flow cytometric analysis, we found three distinct patterns of CD200 expression: (1) strong to dim positive CD200 expression by neoplastic cells in CLL/SLL (16/16 cases) and lymphoplasmacytic lymphoma (30/32); (2) variable CD200 expression [positive (5/18), dim positive (5/18), negative (8/18)] in marginal zone lymphoma, including MALT lymphoma; (3) negative to dim positive CD200 expression in mantle cell lymphoma (11/11) and follicular lymphoma (28/29). Fifteen cases of various other B cell lymphoproliferative disorders were studied for CD200 expression. The findings were similar to those observed in our prior immunohistochemical analysis, except for cases of marginal zone lymphoma, which were previously found to be uniformly negative for CD200 expression.
Conclusions: CD200 is expressed in a number of B cell lymphoproliferative disorders, can be assessed by flow cytometric as well as immunohistochemical analysis, and may be helpful in the differential diagnosis of a number of these neoplasms. CD200-positive B cell-derived neoplasms may have a survival advantage conferred by CD200 expression, so CD200 expression may have prognostic significance. A CD200 antibody-derived immunotherapeutic agent in clinical trial to treat CLL/SLL and multiple myeloma may be of potential utility for the treatment of other CD200-positive B cell lymphoproliferative disorders.
Category: Hematopathology

Monday, March 19, 2012 1:00 PM

Poster Session II # 208, Monday Afternoon


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