Abstract
Intraperitoneal infection of mice with two strains of Yersinia enterocolitica resulted in an inflammatory response and immunomodulation which appeared to be related to the invasive properties of the bacteria. The primary antibody response to sheep erythrocytes was enhanced by noninvasive cultures of Y. enterocolitica (serotype O:4-33 grown at 22C and at 37C, and serotype O:3 grown at 37C), when given at the same time or two days after the antigen (invasiveness was tested on HeLa cells). In contrast, invasive cultures of serotype O:3 grown at 22C, injected three days before the antigen suppressed the antibody response; enhancement was caused by these cultures only when given on the day of immunization. Delayed-type hypersensitivity to sheep erythrocytes was also suppressed by invasive cultures of Y. enterccolitica. These data indicate that the temperature of growth as well as some serotype-linked factors play a role in immunomodulation by Y. enterocolitica.
