Listeria monocytogenes in laboratory mice: a model of short-term infectious and pathogenic processes controllable by regulated protective immune responses

The mammalian immune system is an integrated network of tissues, leukocytes and effector and regulatory molecules. All these components operate i) to maintain the proper structure of and processes expressed by each tissue, and ii) to protect the hosts from those microorganisms that generally invade them as part of their life cycle. Among the invading micso-organisms, Listeria monocytogenes (L. monocytogenes) can persist as a live organism independent of the host, and is, thus, able to drive shortterm infectious and pathogenic processes that are controlled by integrated innate and adaptive protective immune responses driven by CD8 and CD4 type 1 T lymphocytes acting on non-T non-B leukocytes. Although the effector functions and the fine specificity of T lymphocytes have been more and more characterized, an understanding of the precise regulation of both leukocyte traffic and T-lymphocyte migration depends on knowledge of the early tissue distribution of L. monocytogenes, points that are addressed in this review.