Human eosinophils and parasitic diseases. II. Characterization of two cell fractions isolated at different densities

A new procedure, based on centrifugation through multiple discontinuous gradients of polyvinylpyrrolidone-coated silica particles has been developed for the separation of almost pure eosinophils from blood samples of healthy donors. When this technique is employed for the purification of eosinophils from the peripheral blood of patients with parasitic diseases, two cell fractions almost pure in eosinophil granulocytes are harvested at different densities. Preliminary results, concerning the characterization of these cell fractions, indicate that in the terms of detectable membrane receptors and K cell activity, two distinct eosinophil subpopulations can be recognized.