title: Tac-positive, HTLV-negative, T helper phenotype chronic lymphocytic leukemia cells.
abstract: In this report we describe an Italian patient with chronic T cell leukemia whose proliferating cells were mature T lymphocytes with a helper phenotype (T helper phenotype chronic lymphocytic leukemia, or Thp-CLL). Unlike other reported cases of Thp-CLL, fresh leukemic cells from this patient were positive with the anti-Tac monoclonal antibody, which recognizes the receptor for interleukin-2 (IL-2). Thus, the phenotype of these cells was similar to that expressed by Japanese patients with adult T cell leukemia (ATL) (OKT3+, OKT4+, OKT8-, Tac+). However, the Italian patient had Thp-CLL, not ATL, since his cells, unlike ATL cells, lacked human T cell leukemia virus (HTLV-I)-related DNA sequences. The Tac receptor, which appears to be modulated in vitro by the anti-Tac antibody, was biologically inactive, since the patient's cells did not respond in vitro to IL-2. In addition, they also failed to demonstrate in vitro functional activities. The clinical course was aggressive, as usual, for both Thp-CLL and ATL. Taking advantage of the description of this case, some similarities and differences between Thp-CLL and ATL are discussed, focusing on the importance of screening of HTLV-I in the differential diagnosis.
authors.forename: F
authors.initials: F
authors.lastname: Pandolfi
authors.forename: G
authors.initials: G
authors.lastname: De Rossi
authors.forename: A
authors.initials: A
authors.lastname: Ranucci
authors.forename: G
authors.initials: G
authors.lastname: Bonomo
authors.forename: D
authors.initials: D
authors.lastname: Pasqualetti
authors.forename: M
authors.initials: M
authors.lastname: Napolitano
authors.forename: V
authors.initials: V
authors.lastname: Manzari
mesh_terms: D000368:Aged; D000954:Antigens, Surface / Q000032:analysis*; D004279:DNA, Viral / Q000032:analysis; D017977:Deltaretrovirus / Q000235:genetics; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D007945:Leukemia, Lymphoid / Q000276:immunology* / Q000382:microbiology; D008213:Lymphocyte Activation; D008297:Male; D010641:Phenotype; D010835:Phytohemagglutinins / Q000494:pharmacology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
chemical_list: D000954:Antigens, Surface; D004279:DNA, Viral; D007376:Interleukin-2; D010835:Phytohemagglutinins; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7