title: Capping of ricin-binding sites does not influence phagocytosis in human polymorphonuclear leukocytes.
abstract: Human polymorphonuclear leukocytes (PMN'S) were incubated at 0 degrees C with ferritin-conjugated ricin and warmed to 37 degrees C to induce capping of the ricin-binding sites. The PMNs were then allowed to phagocytose yeast or Staphylococcus epidermidis for 15 min, and processed for electron microscopy. Phagocytic uptake, granule fusion, and the fate of lectin-bound membrane were quantified by morphometry. Ricin-capped PMNs phagocytosed as extensively as untreated PMNs. Particles were ingested almost exclusively with a lectin-free portion of the plasmalemma. Fusion of granules with phagocytic vacuoles was not affected by ricin-induced capping. This indicates that ricin-binding sites are not involved in particle recognition and uptake.
mesh_terms: D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D007962:Leukocytes / Q000502:physiology*; D010587:Phagocytosis / Q000187:drug effects; D012276:Ricin / Q000378:metabolism / Q000494:pharmacology
chemical_list: D012276:Ricin