title: Decrease of memory T helper cells (CD4+ CD45R0+) in hairy cell leukemia.
abstract: Patients with hairy cell leukemia (HCL) are prone to opportunistic infections, which suggests an impaired T-cell functioning. To investigate a possible mechanism of such an impairment, we determined the numbers of naive and memory T cells by measuring the expression of CD45R0 on CD4+ and CD8+ T cells in 23 HCL patients. As control, 13 healthy subjects and 13 patients with other chronic B-cell leukemias were studied. In HCL patients with active disease, the percentage of CD4+ CD45R0+ T cells was significantly lower compared to healthy subjects (41% versus 57%, p = 0.01). Also the absolute numbers of CD4+ CD45R0+ T cells were reduced (396 x 10(6)/l versus 615 x 10(6)/l, p = 0.02) compared to healthy subjects, whereas within the CD8+ subset no differences were found. A contrasting elevation of percentages and numbers of CD45R0-expressing T cells (p < 0.0001) was seen in patients with chronic lymphocytic leukemia or leukemic non-Hodgkin's lymphoma. No relationship between CD4+ CD45R0+ and splenectomy, treatment with alpha-interferon or monocyte numbers was found in the HCL population. Despite the fact that the underlying mechanism of the reduced expression of CD45R0 in CD4+ T cells remains unclear, our observations may contribute to the understanding of an impaired T-cell functioning in HCL.
authors.affiliation: Department of Hematology, University Hospital Leiden, The Netherlands.
authors.forename: F A
authors.initials: FA
authors.lastname: van der Horst
authors.forename: A
authors.initials: A
authors.lastname: van der Marel
authors.forename: G J
authors.initials: GJ
authors.lastname: den Ottolander
authors.forename: H C
authors.initials: HC
authors.lastname: Kluin-Nelemans
mesh_terms: D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D007943:Leukemia, Hairy Cell / Q000276:immunology* / Q000473:pathology; D017493:Leukocyte Common Antigens / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D017493:Leukocyte Common Antigens