Bacterium-induced autoimmune reactivity.

Evidence is growing that autoimmune reactivity results from a combination of endogenous (e.g. MHC type) and environmental factors. Our experimental study focuses on the induction of autoimmune reactivity by microbial factors. Splenic formation and serum levels of anti-erythrocyte antibodies and circulating immune complexes were taken as parameters. It was found that experimental infection of mice with Escherichia coli and Salmonella typhimurium was accompanied by clear signs of autoimmune reactivity, smooth bacteria being almost ten times as potent as rough mutant strains. An attempt was made to correlate the data obtained with live bacteria to their corresponding endotoxins. It was concluded that the induction of more prominent autoimmune reactivity by smooth bacteria must be ascribed to a longer survival time in vivo. Our data support the view that bacterium-derived factors are involved in the etiology (and possibly also the course) of autoimmune diseases.