Expression of the IFNα receptor in hairy cell leukaemia

Summary. The expression of IFNα receptors on the surface of hairy cell leukaemia cells was studied using affinity crosslinking methods, flow cytometry with a recently produced anti‐IFNα receptor monoclonal antibody (IFNaR3), and binding techniques. IFNα receptors were detected by flow cytometry and affinity crosslinking in eight cases showing a normal receptor structure with ¹²⁵ I‐IFNα2‐receptor complexes with molecular weights of 210, 130 and 110 kD. The hairy cell leukaemia cells from one patient did not express IFNα receptors as determined by flow cytometry, affinity crosslinking and binding studies. Northern blot analysis showed expression of mRNA for the gene coding for the putative IFNα receptor in all cases studied, including the patient with lack of IFNα receptor expression on hairy cells. This patient was refractory to IFNα2 treatment. Our data suggest that lack of expression of IFNα receptors in rare cases may be associated with refractoriness to IFNα2 therapy.