Rickettsiae and hosts.
Protective immunity to Rickettsia tsutsugamushi in a murine model is dependent upon the development of cell mediated immunity, as demonstrated by lymphocyte transfer, production of lymphokines and -interferon by thymus-derived lymphocytes, activation of macrophages by lymphokines and demonstration of delayed-type hypersensitivity response following exposure to these organisms. Infection of mice with small numbers of Rickettsia typhi inoculated by a peripheral route leads to a more complex pattern of immune development, with a distinction between resistance to local and systemic infection. Nevertheless, thymus-derived lymphocytes and activated macrophages play a major role in modulating pathogenesis of infection, and delayed-type hypersensitivity responses are evident. Spotted fever group rickettsiae also elicit a cell-mediated response in rodents, and protection against Rickettsia conorii infection has been achieved by adoptive transfer of thymus-derived lymphocytes from immune animals. Limited studies with Rickettsia akari suggest that activation of mouse macrophages is critical to host survival following infection with this organism.
Osterman
J V
JV
D000818:Animals; D006968:Hypersensitivity, Delayed; D007111:Immunity, Cellular; D007114:Immunization; D007372:Interferons / Q000096:biosynthesis; D008214:Lymphocytes / Q000276:immunology; D008222:Lymphokines / Q000502:physiology; D008262:Macrophage Activation; D051379:Mice; D012282:Rickettsia Infections / Q000276:immunology*; D012612:Scrub Typhus / Q000276:immunology
D008222:Lymphokines; D007372:Interferons