Shwartzman reaction in endotoxin-resistant rabbits induced by heterologous endotoxin.

Moderate resistance to Escherichia coli and Serratia marcescens endotoxin was induced in rabbits. The E. coli endotoxin-resistant rabbits did not respond with a Shwartzman reaction if the skin preparation was carried out by E. coli endotoxin and the provocation by Serratia endotoxin. However, the same animals showed definite haemorrhagic reactions if their skin was prepared by endotoxin from other serological types, e.g. Serratia or Salmonella typhi endotoxin. Serratia endotoxin resistant rabbits did not display the Shwartzman reaction if the skin preparation was carried out by Serratia endotoxin. On the contrary, they displayed marked Shwartzman reactions at the sites of the skin preparation with E. coli endotoxin. The provocation of this haemorrhagic reaction could be carried out either by E. coli or by Serratia endotoxin. The above results point to the possibility of the role of an immunological specificity in the skin preparation of the Shwartzman phenomenon. No such specificity could be demonstrated with regards to the intravenous provocation of the reaction. The immunospecificity (serological specificity) in the preparation of the Shwartzman reaction is limited, because it disappears if a higher degree of resistance is established. The immunospecificity in resistance or in sensitivity is dose-dependent. By raising the preparing or provoking doses, the Shwartzman reaction can be induced by heterologous or homologous endotoxins in rabbits that have a higher degree of resistance. The possible cause is discussed.