To investigate whether differences in cytokine expression explain enhanced bacterial clearance in Nippo mice, intraperitoneal levels of three cytokines that regulate the host response to bacterial infections (TNF-α, IL-6, and IL-1ß) were compared at baseline and 4 and 24 h after K. pneumoniae infection in Nippo and unparasitized mice. This evidence concerns the gene IL1B and bacterial infectious disease.