Human eosinophils and parasitic diseases: light and electron microscopy evidence of interaction with sheep erythrocyte.

The aim of this study was to investigate the possible formation of spontaneous rosettes between human eosinophils and sheep erythrocytes. In patients with parasitic diseases a percentage of 15.7 +/- 6 (range 6-23%), eosinophils were able to form rosettes. Each rosette showed as few as four to eight erythrocytes attached per eosinophil. Two types of interaction were observed at the electron microscope: point attachments and large surface contacts. In patients with non-parasite induced eosinophilia the formation of rosettes is decidedly below the above-mentioned percentage (less than 2%) or totally absent. It follows that during parasitic infections with blood eosinophilia, whatever the mechanism responsible, the formation of spontaneous rosettes could be diagnostic significance and might reflect qualitative or quantitative modifications in the eosinophil population.