Hyper-reactivity of rabbits sensitized with Bartonella bacilliformis.

Mitchell, Paul D. (West Virginia University Medical Center, Morgantown), and John M. Slack. Hyper-reactivity of rabbits sensitized with Bartonella bacilliformis. J. Bacteriol. 92:769-779. 1966.-Sensitization with viable cells of Bartonella bacilliformis increased the susceptibility of rabbits to the lethality of subsequently administered Bartonella metabolites. In animals sensitized with 3 weekly doses of the organism, this susceptible state of hyper-reactivity was maximal between 4 and 14 days postsensitization (primary hyper-reactive state) and persisted for at least 4 weeks, after which the animals were nonreactive (tolerant state). However, on the 84th day, the susceptible state could once again be demonstrated (secondary hyper-reactive state). Animals sensitized with only 1 or 2 weekly doses of the organism were rendered nearly as susceptible, but the time interval between the primary and secondary states of hyper-reactivity was much shorter, indicating that the hyper-reactive states were dependent upon the degree of sensitization. Symptoms displayed by such animals demonstrated an association with endotoxic shock and an anaphylactic or immediate hypersensitive response, the reaction frequently being severe enough to lead to the death of the animal within 24 hr. The histological findings were those of the generalized Shwartzman phenomenon with indications of shock. Such hyper-reactive animals produced an early-occurring, precipitating antibody specific for the somatic, endotoxic component of various gram-positive microorganisms. Injection of sera from the hyper-reactive animals into normal, nonsensitized animals resulted in a passive, hyper-reactive state in the latter animals. A distinct relationship between the levels of specific antibody and the degree of demonstrable hyper-reactivity was observed. This relationship is discussed relative to the histological findings of the hyper-reactive animals.