Lymphokine stimulated macrophages inhibit intracellular Chlamydia psittaci replication by mechanisms distinct from intracellular inhibition of Toxoplasma gondii replication.

Abstract

Chlamydia and Toxoplasma are obligate intracellular parasites that replicate within macrophages and other eucaryotic host cells. Although chlamydia are procaryotes and Toxoplasma are eucaryotes, these organisms have several features in common during their intracellular growth and development. Each of these parasites is taken into the host cell by an endocytic mechanism that resembles phagocytosis (1,7), and each subverts normal phagocytic function by inhibiting fusion of host cell lysosomes with parasite-containing vacuoles (3,5). The mechanisms involved in this inhibition are not known, although Eissenberg and Wyrick (2) have reported that inhibition of fusion in peritoneal macrophages challenged with C. psittaci and either Saccharomyces ceriviciae or Escherichia coli was restricted to chlamydiae-containing vesicles. Chlamydiae and Toxoplasma remain within membrane bound vesicles during their entire intracellular development. Toxoplasma replicate by a process called endodyogeny. Chlamydiae first differentiate from a metabolically inactive infective form called an elementary body to an intracellular reticulate body, then grow and divide by binary fission forming a microscopically visible inclusion.KeywordsPeritoneal MacrophagePhorbol Myristate AcetateChlamydia TrachomatisPhorbol Myristate AcetateToxoplasma GondiiThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.