Hairy cell leukemia-associated antigen (HC2) is an activation antigen of several hemopoietic cell lineages, inducible on monocytes by IFN-gamma.
The HC2 Ag is defined by a mAb raised against leukemic B lymphocytes from a patient with hairy cell leukemia (HCL). This 60 to 70-kDa Ag was immunoprecipitated from EBV-transformed B lymphoblastoid cell lines, from HCL-B cells, from the HUT-102 T cell line infected with HTLVI, and from activated monocytes. A binding assay with radioiodinated Fab' anti-HC2 confirmed this cellular distribution of the Ag and demonstrated 500 to 3000 binding sites on resting T cells, 300 to 11,000 binding sites on non-T cells, less than 3000 binding sites on chronic lymphocytic leukemia B cells, and 29,000 to 223,000 binding sites on HCL-B cells. PMA plus anti-CD3 up-regulated HC2 expression on T cells and IFN-gamma up-regulated expression on monocytes. On B cells, EBV transformation may result in HC2 expression, and antibody to HC2 has been found to inhibit B cell differentiation and proliferation. The combined results suggest an important role for the HC2 membrane-associated Ag on cells responsible for the immune response.
Posnett
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Department of Medicine, Cornell University Medical College, New York, NY 10021.
Duggan
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McGrath
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D000911:Antibodies, Monoclonal / Q000276:immunology; D000943:Antigens, Differentiation / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007943:Leukemia, Hairy Cell / Q000276:immunology*; D008213:Lymphocyte Activation; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology*; D011233:Precipitin Tests; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D011948:Receptors, Antigen, T-Cell; C060024:hairy cell leukemia antigen, HC2, human; D007371:Interferon-gamma