Antibody Formation at Various Times After Previous Treatment of Mice With Endotoxin

Abstract

The effects of sheep red blood cells or endotoxins on numbers of hemolysin-forming spleen cells were studied in mice previously injected with a small dose of endotoxin. One day after pretreatment the response to sheep red cells was greater than normal and the response to endotoxin was smaller than normal. At 10-12 days after pretreatment, the response to sheep red cells was normal but the response to endotoxin, given alone or together with sheep red cells, was greater than normal. Of 5 endotoxin preparations studied, only a protein-free endotoxin failed to alter reactivity to a subsequent in-jection of the same endotoxin. The implications of these findings for the hypothesis that adult host reactivity to endotoxins is contributed to by an acquired delayed hypersensitivity are discussed.