CD2 is expressed by a subpopulation of normal B cells and is frequently present in mature B‐cell neoplasms

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Abstract
Background CD2 is expressed by T and natural killer (NK) cells and has been reported in T/NK cell lineage neoplasms as well as in immature B‐lymphoblastic and myeloid leukemias. Although CD2+ B‐cells have been identified in normal fetal and postnatal thymus, they have not been reported in adults. Methods We retrospectively reviewed flow cytometric immunophenotypic data on consecutive low‐grade B‐cell leukemias and lymphomas to investigate the frequency of CD2 expression. We also reviewed samples from normal healthy donors to determine whether there is a normal CD2+ B‐cell population. Results CD2 expression (partial or complete) was observed in 13 of 83 (16%) chronic lymphocytic leukemias (CLL), 16 of 29 (55%) follicle center lymphomas (FCL), 3 of 12 (25%) hairy cell leukemias (HCL), 0 of 6 mantle cell lymphomas (MCL), 8 of 28 (29%) large cell lymphomas (LCL), and in 0 of 5 marginal zone/mucosa‐associated lymphoid tissue lymphomas (MZL/MALT). We determined that 5.74 ± 2.46% (mean ± SD) of normal peripheral blood B cells and 6.48 ± 1.62 % (mean ± SD) of normal bone marrow B cells coexpress CD2. Conclusions CD2 expression in B‐cell neoplasia is a more prevalent phenomenon than previously appreciated. Normal CD2+ B‐cell populations are observed in adults and may represent the nonmalignant counterpart of CD2+ B‐cell neoplasms. Cytometry (Clin. Cytometry) 50:243–248, 2002. Published 2002 Wiley‐Liss, Inc.