title: Hairy cell leukemia-associated antigen LeuM5 (CD11c) is preferentially expressed by benign activated and neoplastic CD8 T cells.
abstract: LeuM5 antigen (CD11c, p150.95) expression, widely used as an immunodiagnostic marker for B-cell hairy cell leukemia, was examined on benign, normal peripheral blood T cells before and after stimulation in vitro with phytohemagglutinin and on a large, diverse panel of 73 T-cell neoplasms. Resting T cells lacked LeuM5. Intracytoplasmic LeuM5 was detectable at 3 to 4 days and surface membrane LeuM5 was detectable continuously between 5 and 17 days on greater than or equal to 20% CD3 cells (maximum, 42% CD3 cells at 10 days) after activation. Two-color flow cytometric analysis of the activated T cells demonstrated that a maximum of 60% CD8 but only 25% CD4 cells expressed LeuM5; the mean percentage of LeuM5+ CD8 cells was 44% compared with 12% LeuM5+ CD4 cells. A variable proportion of the neoplastic T cells in 19 of 73 (26%) T-cell neoplasms were LeuM5+. Twelve of 18 CD4-CD8+ (67%) but only 5 of 40 CD4+ CD8- T-cell neoplasms expressed LeuM5. These studies demonstrate that the LeuM5 antigen is 1) expressed in association with T-cell activation, 2) preferentially expressed by activated CD8 cells, and 3) variably expressed by neoplastic T cells, but particularly by those exhibiting the CD4- CD8+ phenotype.
authors.affiliation: Department of Pathology Columbia University College of Physicians and Surgeons, New York, NY 10032.
authors.forename: A
authors.initials: A
authors.lastname: Chadburn
authors.forename: G
authors.initials: G
authors.lastname: Inghirami
authors.forename: D M
authors.initials: DM
authors.lastname: Knowles
mesh_terms: D000943:Antigens, Differentiation / Q000276:immunology*; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016827:CD8 Antigens; D015870:Gene Expression; D006801:Humans; D016167:Integrin alphaXbeta2; D007943:Leukemia, Hairy Cell / Q000276:immunology*; D007945:Leukemia, Lymphoid / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008223:Lymphoma / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D010835:Phytohemagglutinins / Q000494:pharmacology; D016028:Receptors, Leukocyte-Adhesion / Q000276:immunology*; D012878:Skin Neoplasms / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000378:metabolism / Q000473:pathology
chemical_list: D000943:Antigens, Differentiation; D015214:Antigens, Differentiation, Myelomonocytic; D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; D016827:CD8 Antigens; D016167:Integrin alphaXbeta2; D010835:Phytohemagglutinins; D016028:Receptors, Leukocyte-Adhesion