title: CD2 is expressed by a subpopulation of normal B cells and is frequently present in mature B-cell neoplasms.
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.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000276:immunology* / Q000378:metabolism; D018801:CD2 Antigens / Q000276:immunology* / Q000378:metabolism; D018450:Disease Progression; D005434:Flow Cytometry; D006801:Humans; D015448:Leukemia, B-Cell / Q000175:diagnosis / Q000276:immunology* / Q000378:metabolism; D007943:Leukemia, Hairy Cell / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D008221:Lymphoid Tissue / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D016393:Lymphoma, B-Cell / Q000175:diagnosis / Q000276:immunology* / Q000378:metabolism; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D020522:Lymphoma, Mantle-Cell / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D012016:Reference Values; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor; D018801:CD2 Antigens