STUDIES ON ENDOTOXIN HYPERREACTIVITY IN MICE INFECTED WITH BRUCELLA ABORTUS

Endotoxin sensitivity was investigated in mice infected with Brucella abortus. A hyperreactive state was observed at 12 hr after intravenous injection with a large dose of Brucella.Ability of endotoxins of a variety of bacterial species to elicit endotoxin hyperreactivity was compared in mice infected with Brucella 24 hr previously. Endotoxins of enteric bacteria were most efficient, that of virulent Brucella was moderately efficient, and that of low-virulent Brucella was not efficient.The hyperreactive state after injection with different doses of 3 strains of Brucella abortus, virulent, low-virulent and avirulent, was compared. A close correlation was found between hyperreactivity to endotoxin and the severity of infection. Appearance and degree of endotoxin hyperreactivity depended on virulence and dose of Brucella injected.A slight degree of hyperreactivity was observed 24 hr after the injection with live avirulent Brucella or formalin-killed Brucella. Intravenous and intraperitoneal injections were much more effective than infections from other routes. Relationship between induction of endotoxin hyperreactivity and deposition of brucellae in the liver and spleen is discussed.