Fc Receptor Bearing 'Hairy Cells' of Leukaemic Reticuloendotheliosis Bind Soluble Antigen-Antibody Complexes and Adhere to Immobilized Complexes, but Fail to Mediate Antibody Dependent Cellular Cytotoxicity

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Abstract
Most hairy cells from 3 patients with leukemic reticuloendotheliosis were adherent cells bearing surface immunoglobulin [sIg], complement receptors and Fc receptors [FcR]. Highly purified populations of malignant hairy cells, which readily bound soluble antigen-antibody complexes in suspension and were able to adhere to immobilized antigen-antibody complexes, were examined for their ability to mediate ADCC [antibody dependent cellular cytotoxicity]. Two patients with greater than 90% FcR positive cells failed to mediate ADCC. When initially examined, a 3rd patient, with fewer malignant cells, demonstrated a less marked impairment of cytolysis. When re-examined at a later date, this patient had an increased number of hairy cells and concomitantly demonstrated more impaired ADCC effector cell activity. Absorption of sIg-bearing cells onto plastic surfaces coated with goat anti-human Ig resulted in a complete depletion of FcR, sIg positive, hairy cells. The remaining nonadherent fraction, containing 5.5% FcR positive, sIg negative cells, was able to mediate ADCC as effectively as the normal controls. Although FcR bearing hairy cells readily bind soluble antigen-antibody complexes and adhere to immobilized complexes, they were unable to mediate ADCC.