RT Journal Article SR Electronic(1) A1 Ruiz-Bravo, Alfonso A1 Moreno, Encarnación A1 Jiménez-Valera, Marı́aYR 2001 T1 Intestinal infection of BALB/c mice with Yersinia enterocolitica O9 causes major modifications in phenotype and functions of spleen cells JF Microbiology, VO 147 IS 11 SP 3165 OP 3169 DO https://doi.org/10.1099/00221287-147-11-3165 PB Microbiology Society, SN 1465-2080, AB Yersinia enterocolitica serotype O9 may cause a persistent intestinal infection with few or no symptoms in humans and in BALB/c mice. The present study demonstrated profound alterations in the immune status of BALB/c mice infected with Y. enterocolitica O9. Infected mice developed splenomegaly and phenotypic analysis of spleen cells revealed increases in CD3+ total T cells, CD4+ helper T cells, CD8+ cytotoxic T cells and CD11b+ phagocytic cells. Spleen cells from infected mice exhibited impaired responses to mitogens and suppressed the proliferation of normal splenocytes in response to mitogens. Suppression of responses to concanavalin A and heat-killed yersiniae was associated with increased production of gamma interferon and reactive nitrogen intermediates. Y. enterocolitica-infected mice resisted challenge with a lethal dose of the intracellular pathogen Listeria monocytogenes. These findings suggest that infection of mice with Y. enterocolitica O9 induces gamma-interferon-secreting cells that promote macrophage activation, mediating resistance to infection with L. monocytogenes, and macrophage production of reactive nitrogen intermediates, which results in in vitro inhibition of lymphocyte response to mitogens., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-147-11-3165