Morphological changes associated with the extrusion of protein induced in the polymorphonuclear leucocyte by staphylococcal leucocidin

Abstract

Leucocytes treated with leucocidin have been examined with the light-microscope and electron microscope. When calcium is present in the medium the cells lose their granules and vesicles can be seen in the cytoplasm and in the medium. Some of the vesicles are fused to the surface of the cell. In the absence of calcium the random brownian motion of the granules persists for at least 30 min. There is no degranulation and vesicles cannot be observed. When calcium is added to the leucocidin-treated cells after incubation in calcium-free medium the brownian motion stops, some of the granules disappear and vesicles can be seen in the cytoplasm. The specific activities of some enzymes in the granules and the vesicles have been measured. It is suggested that the vesicles are produced from granules, some of which have discharged part of their contents. The conversion of the granules into vesicles may be simultaneous with the fusion of the granule and the cell surface. It is suggested that the release of protein from the vesicles follows rupture of the membrane at the site of fusion, or occurs by a permeability change at the site of fusion or by both of these processes.