Phenotypic Analysis of Hairy Cell Leukemia: “Variant” Cases Express the Interleukin-2 Receptor β Chain, But Not the α Chain (CD25)

• Published in: Blood 1993-07, Vol.82 (2), p.528-535
• Main Authors: de Totero, Daniela, Tazzari, Pier Luigi, Lauria, Francesco, Raspadori, Donatella, di Celle, Paola Francia, Carbone, Anna, Gobbi, Marco, Foa, Robert
• Format: Article
• Language: English
• Subjects: Adult; Aged; Antibodies, Monoclonal; B-Lymphocytes - immunology; B-Lymphocytes - pathology; Base Sequence; Biological and medical sciences; Cell Membrane - immunology; Female; Fluorescent Antibody Technique; Hematologic and hematopoietic diseases; Humans; Leukemia, Hairy Cell - immunology; Leukemia, Hairy Cell - pathology; Leukemia, Lymphocytic, Chronic, B-Cell - immunology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Male; Medical sciences; Middle Aged; Molecular Sequence Data; Phenotype; Receptors, Interleukin-2 - analysis; Receptors, Interleukin-2 - chemistry; Receptors, Interleukin-2 - genetics; RNA, Messenger - analysis
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V82.2.528.528

Hairy cell leukemia (HCL) is a B-cell chronic lymphoproliferative disorder in which the pathologic cells show a strong expression of CD25 (interleukin-2 [IL-2] receptor α chain or p55). “Variant” cases of HCL, characterized by hyperleukocytosis, neoplastic elements with a prominent nucleolus and a higher nucleo/cytoplasmic ratio, and an easily obtained bone marrow aspirate, lack surface CD25 determinants. Limited information is available on the expression of the IL-2 receptor β chain (p75) on normal and neoplastic B cells. In this study, we have assessed by immunofluorescence and mRNA analysis the presence of the IL-2 receptor α and β chains on 12 cases of classic HCL, as well as on 3 variant cases. The results obtained show that, while the α chain of the IL-2 receptor is present only on classic HCL, the IL-2 receptor β chain (p75) is expressed on both the classic and variant form. Unlike hairy cells, only 8 of the 15 B-cell chronic lymphocytic leukemia cases tested showed a weak expression of the p75 antigen on a small proportion of cells. Purified B lymphocytes from normal healthy controls, as well as Epstein-Barr virus-transformed lymphoblastoid cell lines, showed a weak staining for the p75 determinant, while being CD25–. The results of this study suggest that the expression of the α and β chains of the IL-2 receptor appears to be upregulated or downregulated during the process of B-cell–lineage activation and differentiation.