Tac-positive, HTLV-negative, T helper phenotype chronic lymphocytic
leukemia cells
F Pandolfi, G De Rossi, A Ranucci, G Bonomo, D Pasqualetti, M Napolitano and V Manzari
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.
Volume 65,
Issue 6,
pp. 1531-1537,
06/01/1985
Copyright © 1985 by The American Society of Hematology
