Induced sensitization of normal laboratory animals to Brucella abortus endotoxin.

A Boivin preparation of Brucella abortus, unlike common enterobacterial endotoxins, failed to depress water intake or increase numbers of hemolysin-producing spleen cells in mice, or to cause delayed inflammatory reactions in rabbit skin. Reactivity to the B. abortus endotoxin was found only in animals which were previously given the endotoxin with, but not necessarily in, complete Freund's adjuvant. Previous treatment with the endotoxin in saline or with only the adjuvant was ineffective. Sensitization appeared within 10 days and waned after 5 weeks. Passive sensitization was obtained with sensitized donor spleen cells but not with serum. Serum antibody titers did not correlate with the appearance and disappearance of sensitization.