[1442] CD1c Expression in B Cell Lymphoproliferative Disorders

Erica Martin, Howard Meyerson. University Hospitals Case Medical Center, Cleveland, OH

Background: CD1c is known to be expressed on marginal B cells of the spleen. We hypothesized that CD1c might be a useful marker of marginal zone B cell lymphomas (MZL) and may be of utility in distinguishing MZLs from other low grade B cell lymphoproliferative disorders.
Design: The expression level of CD1c on lymphoma cells was evaluated by flow cytometry on 192 B cell lymphoproliferative disorders from 2009-2012 at University Hospitals Case Medical Center. Levels of CD1c expression on B cells in the peripheral blood from normal samples (N=10) was also examined and compared with that on the B cell lymphoproliferative disorders.
Results: On average, CD1c was expression on 26% of peripheral blood B lymphocytes. The level of expression of CD1c on the CD1c+ subset of B cells in peripheral blood was moderate (mean fluorescent intensity (MFI) = 445, N=10). By subjective visual evaluation CD1c expression was deemed dim to moderate. The overall mean level of fluorescence of CD1c on marginal zone lymphoma (MZL) (n=35, average MFI = 246) was higher than that on mantle cell lymphoma (MCL) (n=10, average MFI =88) and chronic lymphocytic leukemia (CLL) (n=96, average MFI = 46). 46% (16/35) of MZL expressed CD1c at moderate levels (CD1c mod) (>200 MFI) compared to 5% (5/96) of CLLs and 10% (1/10) of MCLs. Expression was heterogeneous in hairy cell leukemia (n=4, average MFI = 187) and unclassifiable CD5 (+) B cell lymphoproliferative disorders (n=9, average MFI =161). Expression of CD1c on CD1c mod MZL (average MFI = 431) was comparable to the expression of CD1c on the normal CD1c (+) B cell subset in peripheral blood. The remaining MZL cases expressed low levels of CD1c (average MFI =91) similar to CLL and MCL and minimally above the level observed on CD1c (-) peripheral blood B cells.
Conclusions: CD1c is expressed at moderate levels on a large portion of MZL and may be of use in distinguishing MZL from other low grade B cell lymphoproliferative disorders. Heterogeneity of CD1c expression in MZL cases may indicate a separate B cell origin for CD1c (+) and CD1c (-) MZL neoplasms.
Category: Hematopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 264, Tuesday Afternoon


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