Defective interferon-gamma production in patients with hairy cell leukaemia

Patients with hairy cell leukaemia (HCL) have an increased susceptibility to intracellular pathogens, such as mycobacteria and Listeria. Although several abnormalities of T-cell populations have been described in HCL, the effector mechanism responsible for the increased susceptibility to infections is not known.

Blood was collected from 11 patients with HCL and 22 age- and gender-matched volunteers. Proinflammatory cytokine production by freshly isolated mononuclear cells was stimulated with either lipopolysaccharide or various heat-killed microorganisms. Cytokine concentrations were assessed by specific ELISAs.

We demonstrate that mononuclear cells harvested from HCL patients have a specific defect of IFNgamma production when stimulated with a broad panel of bacterial stimuli. In contrast, the production of other proinflammatory cytokines, such as TNF, IL-1beta and IL-6, did not differ between HCL patients and controls.

The specific defect in IFNgamma production may play a role in the susceptibility of patients with hairy cell leukaemia towards intracellular pathogens.