Dynamics of T Cell, Antigen-Presenting Cell, and Pathogen Interactions during Recall Responses in the Lymph Node

Chtanova, T., et al. 2009. Immunity. 31, 342-355

Speaker: Yu-Cheng Lin (林祐丞)                                  Time: 13:00~14:00, Jan. 6, 2010

Commentator: Chih-Li Lilian Hsu (胥直利老師)        Place: Room 601

Abstract:

Toxoplasma gondii is an intracellular protozoan parasite which is a well established model for the study if T cell response during infection. In previous studies of the authors², they observed that the dynamic of neutrophil moving to infected subcapsular sinus in lymph nodes, and forming swarms to clean the infected CD169⁺ macrophages during primary response to T. gondii infection. Moreover, John, B, et al¹ reported that dynamics of CD8⁺ T cells migrating to T. gondii infected subcapsular sinus, and interacting with antigen-presenting dendritic cells during primary response in early phase of infection. However, the role of memory T cell during recall response due to re-exposure to the parasites in lymph nodes is largely unknown. Therefore, the authors would like to shed light on dynamics of T cell, antigen-presenting cell, and parasite interactions during recall response in lymph nodes. They used an OT1 transgenic mouse model infected by T. gondii and two-photon microscopy to observe those events. They investigated that memory CD8⁺ T cells majorly play a key role in re-exposure to the protozoan. Memory T cells moved more rapidly than naïve T cells toward the subcapsular sinus (SCS) within lymph node near the invaded macrophages, and participated in persistent interaction with infected cells. Tight contacts with infected cells exposed T cells invaded by parasites, which directly relocate from the target cells to the T cells, and the rate of T cell invasion related to an antigen-specific event. The invaded T cell would disseminate other parts of the body and spread the parasites to other tissue. The results provided insight into cellular interactions during recall responses and suggested that the parasites may have a strategy to evade immune system by exploiting the invasion of T cell to promote their own survival.

References:

1.      John, B, et al. 2009. Dynamic imaging of CD8⁺ T cells and dendritic cells during infection with Toxoplasma gondii. PLoS pathog. 5(7), e1000505.

2.      Chtanova, T. 2008. Dynamics of neutrophil migration in lymph nodes during infection. immunity. 29, 487-496.