[Hairy cell leukemia: diagnosis using monoclonal antibodies in flow cytometry]

A prospective study was performed on peripheral EDTA blood samples mailed for screening purposes to a hematology laboratory. Twenty-one samples which were suspicious for hairy cell leukemia (H 6000, Technicon Co. or STKS, Coulter Co.), were evaluated using three diagnostic tests: Microscopic morphology (Giemsa stain); Microscopic controlled inhibition of lymphocyte acid phosphatase by tartrate; Flow-cytometric immunophenotyping with monoclonal antibodies (Epics Profile, Coulter Co.). A characteristic immunophenotype was found on all typical hairy cell leukemias (except two) by positivity of CD11c, CD19, CD22, and CD25. The above-mentioned immunophenotype on peripheral lymphocytes, which can moreover be supported by demonstrating positivity for FMC7, is diagnostic for hairy cell leukemia. It therefore represents a rather straightforward tool to the bone-marrow diagnosis.