Immune Response The innate and acquired immune responses to L. monocytogenes have been studied extensively in mice. Shortly after IV injection, most bacteria are found in Kupffer cells in the liver, with some organisms in splenic macrophages. Listeriae that survive the bactericidal activity of initially infected macrophages grow in the cytosol and spread from cell to cell. In the liver, the result is infection of hepatocytes. Neutrophils are crucial to host defense during the first 24 h of infection, while influx of activated macrophages from the bone marrow is critical subsequently. Mice that survive sublethal infection clear the infection within.
