Lymphocytes are detrimental during the early innate immune response against Listeria monocytogenes

Carrero, J. A. et al. J. Exp. Med. 203: 933-940 (2006)

Speaker：黃思偉                                           Time：11/01/2006 13:10~14:00

Commentator：劉清泉 醫師                                Place：Room 601

Abstract：

Listeria monocytogenes is an intracellular bacterial pathogen which can induce apoptosis, resulting in advantage of its growth and infectivity. In murine listeriosis, an interesting observation has shown that lymphocyte-deficient mice are more resistant to early infection even though they cannot elicit an adaptive immunity. The authors proposed a hypothesis that during listeriosis, lymphocyte apoptosis would be detrimental to the early innate immune response by downregulation of effector reactions. They initially demonstrated that immunocompromised (SCID or RAG2^-/-) mice harbored less colony counts than wild-type mice throughout the fist 4 days. They also engraft wild-type bone-marrow cells into RAG2^-/- mice and found resistance loss by the fourth day. Furthermore, the authors proved that RAG2^-/- mice with engraftment of type I interferon receptor-deficient (IFNabR^-/-) lymphocytes had reduced apoptosis and more susceptibility to listeriosisthan wild-type engrafted mice. Since interleukin-10 (IL-10) produced by macrophages in response to sense of apoptotic bodies is the potential downregulator of immunity, the authors showed that IL-10^-/- mice had increased resistance to listeriosis, and lower level of IL-10 was found in RAG2^-/- and IFNabR^-/- mice infected with Listeria monocytogenes. Therefore, they proved that the presence of lymphocyte apoptosis will downregulate early innate immune response and benefit bacteria with a permissive environment for growth.

References：

1.         Carrero, J. A., B. Calderon, and E. R. Unanue. 2006. Lymphocytes are detrimental during the early innate immune response against Listeria monocytogenes. J Exp Med 203: 933-40.

2.         Carrero, J. A., B. Calderon, and E. R. Unanue. 2004. Type I interferon sensitizes lymphocytes to apoptosis and reduces resistance to Listeria infection. J Exp Med

200: 535-40.