Phenotypic analysis of hairy cell leukemia: "variant" cases express the
interleukin-2 receptor beta chain, but not the alpha chain (CD25)
D de Totero, PL Tazzari, F Lauria, D Raspadori, PF di Celle, A Carbone, M Gobbi and R Foa
Instituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
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 alpha 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 beta 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
alpha and beta chains on 12 cases of classic HCL, as well as on 3 variant
cases. The results obtained show that, while the alpha chain of the IL-2
receptor is present only on classic HCL, the IL- 2 receptor beta 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 alpha and beta chains of the IL-2
receptor appears to be upregulated or downregulated during the process of
B-cell- lineage activation and differentiation.
Volume 82,
Issue 2,
pp. 528-535,
07/15/1993
Copyright © 1993 by The American Society of Hematology
