The extension of the Shwartzman phenomenon to the mouse and some ecological determinants of the single-injection reaction.

The localized Shwartzman reaction has been demonstrated in a highly inbred mouse strain (BSVS). This reaction was produced with marked regularity in these mice by administration of relatively small doses of bacterial endotoxin or other Shwartzman-active agents. It is considered the equivalent of the phenomenon described in the rabbit inasmuch as it has conformed to all the operational and histopathological aspects of the classical reaction that have been tested, including elicitation by various endotoxins, heterologous preparation and provocation, inhibition by anticoagulants, and provocation by antigen-antibody complexes. A reaction similar to the above but differing in its manner of production was also investigated and has been termed the single-injection Shwartzman reaction. This phenomenon was identical with the normal Shwartzman reaction in all ways except for the fact that it was elicited with but a single intradermal injection of bacterial endotoxin. In investigating the lesion it has been demonstrated that inapparent in the gross, but elicitible infection of the lungs with a Gram-negative microflora was uniformly associated with single-injection reactivity. Because of this constant association it has been suggested that a causal relationship exists between the infected state and the skin reaction, not on the basis of known immunological events but on the basis of the Shwartzman mechanism in which the lung flora, demonstrably excited by the preparative injection, appears to mediate natural "endogenous" provocation of the lesion at the prepared skin sites.