SPECIES DIFFERENCE IN THE FEBRILE AND THELEUKOCYTIC RESPONSE TO ENDOTOXIN: ENDOGENOUS HEPATICPYROGEN IN DOGS

Abstract

It has been shown that there exist marked differences between dogs andrabbits in the mechanisms of the febrile and the leukocytic response to en do-toxin. In dogs the leukocytic response seemed to be mainly due to the trapping of neutrophiles in liver and their later release. In the leukocytotic phaseimmature granulocytic form did not predominate and the role played by the ndogenous leukocytosis-inducing factor demonstrated in rabbits was only aminor one. In the state of endotoxin tolerance, although the febrile responsebecame markedly reduced, the leukocytic response remained almost unaltered.Thus the endogenous pyrogen also observable in dogs showed no correlationto the leukopenic response. It was demonstrated that the endogenous pyrogenhas been liberated from the liver in response to endotoxin. It was heat-unstable and pseudoglobulin in nature. The prevention of the endotoxin feverin the tolerant state or by glucocorticoid pretreatment was shown to be theresult of suppression of the hepatic responses to endotoxin including theliberation of the hepatic pyrogen. It was not the result of suppression of thecentral responsiveness.