The biology of hairy-cell leukaemia.

PURPOSE OF REVIEW: The biology of hairy-cell leukaemia is reviewed, focussing first on the hairy cell itself and then on its interactions with the microenvironment.

RECENT FINDINGS: Hairy cells are highly activated clonal B cells related to memory cells, normally resident in the marginal zone of the spleen. Their activation results from multiple stimuli arising from the microenvironment, autocrine cytokines and the still unknown transforming oncogenic event(s) responsible for the disease. Protein kinase Cepsilon is a central player in the activation process.

SUMMARY: The activation of hairy cells makes them unusually sensitive to interferon and nucleosides. Future important research topics include characterization of the oncogenic events responsible for the disease and for its associated differentiation block.