Expression of the IFN alpha receptor in hairy cell leukaemia.

The expression of IFN alpha receptors on the surface of hairy cell leukaemia cells was studied using affinity crosslinking methods, flow cytometry with a recently produced anti-IFN alpha receptor monoclonal antibody (IFNaR3), and binding techniques. IFN alpha receptors were detected by flow cytometry and affinity crosslinking in eight cases showing a normal receptor structure with 125I-IFN alpha 2-receptor complexes with molecular weights of 210, 130 and 110 kD. The hairy cell leukaemia cells from one patient did not express IFN alpha 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 IFN alpha receptor in all cases studied, including the patient with lack of IFN alpha receptor expression on hairy cells. This patient was refractory to IFN alpha 2 treatment. Our data suggest that lack of expression of IFN alpha receptors in rare cases may be associated with refractoriness to IFN alpha 2 therapy.