Different arrangements of phagolysosome membranes which depend upon the particles phagocytized : Observation with markers of the two sides of plasma membranes

Phagolysosome vesicles containing either polystyrene latex (PLP), or PLP plus bovine serum albumin (PLP-BSA), or paraffin oil emulsified with BSA (POE-BSA) were prepared from guinea pig polymorphonuclear leukocytes (gp-PMNL). They were compared using the specific markers of the two sides of the plasma membrane of gp-PMNL characterized previously 1, 2]. Anticell surface IgG (Anti-C-S IgG) which binds exclusively to the outer side of plasma membranes 1] was found to bind to the cytoplasmic side of all three types of phagolysosomes. Anti-100000 g sup IgG which binds exclusively to the cytoplasmic side of plasma membranes of gp-PMNL 1] did not bind to the cytoplasmic side of these phagolysosomes, as shown by immunoferritin technique. On the other hand, influenza virus, which is a marker of the outer surface of plasma membranes 1] bound to the cytoplasmic side of POE-BSA phagolysosomes but not PLP or PLP-BSA phagolysosomes, as demonstrated by electron microscopy. The content of myosin, another marker of the cytoplasmic side of plasma membranes 2], differed in these phagolysosomes, as shown by SDS-polyacrylamide gel electrophoresis: it was very low in PLP- and POE-BSA phagolysosomes but high in PLP-BSA phagolysosomes. Myosin was found on the cytoplasmic side of PLP-BSA phagolysosomes by the improved immunoferritin technique reported previously 3]. These phagolysosomes, containing different particles and having different arrangements of membrane components, showed different efficiencies of fusion with lysosomes. The possible mechanism of the specific fusion of phagosomes with lysosomes was discussed in relation to these different features of phagolysosomal membranes.