Purification of normal human eosinophils using the different binding capacities of blood leucocytes for complexed rabbit IgG.

A method has been developed for separating eosinophils from other types of leucocyte in normal individuals. Erythrocytes are sedimented with dextran, and mononuclear cells are removed on an isotonic density gradient of ficoll and sodium diatrizoate. The eosinophils and neutrophils are then washed and sedimented onto plastic petri dishes coated with human IgG and rabbit anti-human IgG antibody; As neutrophils and monocytes have Fc-binding sites for complexed rabbit IgG they attach to the dishes, and the unabsorbed normal eosinophils which lack this binding site are eluted in a purified suspension. The mean purity of the eosinophils obtained in this way was 70%, range 50-90%, and the mean yield was 49%, range 21-81%. This method provides purified eosinophils from normal people without subjecting them to osmotic or plasma membrane stimulation. Normal eosinophils which are prepared in this way are particularly suitable for studying the ways in which eosinophils became altered in disease states.