Freeze-fracture of circulating human eosinophils

Freeze-fracture has been carried out on peripheral blood from three patients with eosinophilia. Eosinophil granule membranes are characterized by intramembranous particles (IMP) with diameters of 80-150 A. These particles of the granule membrane are consistently larger than the IMP of the plasma membrane which are approximately 80 A in diameter. Cross-fractures of granules showed no evident subgranular inclusions. The difference in size between granule and plasma membrane particles observed in freeze-fracture suggests that studies of eosinophils may be an approach to membrane alterations during phagocytosis.