IL6 and infection: ↓ numbers of T cells, NK cells, neutrophils, and macrophages in the mice inoculated with the heat-killed YB38 treatment compared to control at 4, 4–8, 4–6, and 8 days after infection; IL-6 production was significantly suppressed in the heat-killed YB38-treated group ↑ IgA concentration in YB38-treated group ↓ tissue damage in YB38-treated group