VARIABILITY IN THE INDUCTION OF EXPERIMENTAL ARTHRITIS - YERSINIA ASSOCIATED ARTHRITIS IN LEWIS RATS

Lewis rats of different microbiological status were studied for suscep tibility to experimentally-induced Yersinia associated arthritis. Stat us A rats were serologically positive for Bacillus piliformis, Kilham rat virus and Toolan H-l virus, whereas status B rats were serological ly negative for these same microoganisms. When status A and status B r ats were kept in the same room, incidence of arthritis was low (0-13% for status A rats and 27-33% for status B rats). When status B rats on ly were kept in different environments, increased incidence (up to 89% ) of arthritis was observed. These findings suggest that the microbiol ogical status of the host has an effect on the susceptibility to exper imentally-induced arthritis. They call attention to the need for stric tly defined conditions, including those of the host and the environmen t, in studies on experimental arthritides.