R-fraction as a Biological Principle in the Natural S. abortus equi Endotoxin Preparation / 第二军医大学学报

ABSTRACT

A typical smooth-form lipopolysaccharide (LPS) isolated from Salmonella abortus equi was fractionated into a S (smooth)-and a R (rough)-fraction and their serological and biological properties were investigated. It was shown that S- fraction expressed an O-antigenicity while R-fraction predominately a Rb-antigenicity. The R-fraction was endowed with higher bioactivities than the S-fraction in lethal toxicity, local Shwartzman reaction and pyrogenicity. Both S-and R-fractions were active in inducing mitogenicity to murine spleen cells. A reconstituted LPS preparation with fractionated S-fraction and a trace amount of R-fraction (1% of the original preparation) exhibited a same extent of lethal toxicity as that of the original one. Antr-Ra and -Rb antiserum with a liter of 1?4096 showed a .highly effective protection against the lethal challenge of LPS, indicating that the R-fraction in the natural LPS preparations plays a critical role to the lethality of LPS.