Human eosinophils. Purification and cytotoxic capability of eosinophils from patients with the hypereosinophilic syndrome.

The cytotoxic capability of eosinophils from patients with the hypereosinophilic syndrome (HES) against a variety of target cells was studied utilizing a 5tCr release assay. A separation technique was developed that reproducibly gave eosinophil suspensions of >90% (in many instances >99%) purity from peripheral differential counts of > 10% eosinophils. The method employed density gradient centrifugation to remove mononuclear cells and a nylon wool column incubation to remove neutrophils. Yield was 30%60% of the eosinophils in the initial blood sample and viability was >98%. In ten patients with HES, 16% ± 4% of eosinophils had surface receptors for the Fc portion of lgG (significantly higher than eosinophils from non-HES patients, p < 0.01) and 13% ± 5% of the eosinophils had complement receptors. Eosinophils did not spontaneously lyse erythrocyte targets. However, in the presence of antitarget cell antibody, there was 33% ± 5% and 43% ± 5% cytotoxicity against human and chicken erythrocyte targets, respectively. Low levels of spontaneous cytotoxicity (6% ± 1% and 7% ± 1%) were noted against nucleated Chang liver cell and human heart cell targets, respectively; this killing could be significantly increased to 12% ± 1% and 15% ± 2%, respectively, by adding anti-target cell antibody. Eosinophil cytotoxicity was mediated by lgG but not 1gM anti-target cell antibody, and lysis of lgG(but not 1gM) coated targets was markedly increased by addition of complement on the target cell membrane. Thus this study has found a highly efficient methodology for obtaining purified suspensions of human eosinophils and has delineated certain characteristics and functional capabilities of these cells.