Parasite-directed endocytosis.

Following the attachment of gonococci to human fallopian tube mucosa in organ culture, the gonococci are endocytosed by specialized low columnar epithelial cells, are transported to the base of the epithelial cells, and are subsequently exocytosed into the subepithelial tissues. This transepithelial transport process by which "invasion" of the host occurs appears to be dependent on microbial factors is designated parasite-directed endocytosis to distinguish it from host-directed endocytosis by cells such as macrophages that eventually degrade the parasites. "Invasion" of the host by a number of human pathogens--bacteria (e.g., Neisseria meningitidis, Haemophilus influenzae, and Listeria monocytogenes), viruses, or protozoa--appears to be accomplished by parasite-directed endocytosis.