PASSIVE TRANSFER OF TOLERANCE TO PYROGENICITY OF BACTERIAL ENDOTOXIN

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Abstract
The typical biphasic febrile response of normal rabbits given 2.5 [mu]g Salmonella typhosa 0 901 endotoxin is modified by prior injection of 10 ml of plasma or, less effectively, serum of endotoxin-tolerant donors. The altered response resembles that of the tolerant rabbit: 4 of 25 showed maximum fever at the 2d phase compared with 34 of 37 controls. Fever index was reduced from 584[plus or minus]-34 to 284[plus or minus]-45 (p< 0.001) for plasma and to 440[plus or minus]42 (p < 0.01) for serum. Passive tolerance is still present 24 hours later. This passive transfer of tolerance depends critically upon the manner in which tolerance is induced in the donor; those prepared by sharply increasing daily doses are relatively unsuitable. The blood of tolerant donors given a reticulo-endothelial system (RES)-blocking dose of carbon 4 hours before bleeding, these donors no longer tolerant themselves, still confer tolerance upon normal recipients (fever index 390[plus or minus]26, p < 0.001). The results support the hypothesis that endotoxin tolerance and its transfer are based upon RES function and are independent of antibody or inhibitory factors in the blood.