Abstract:

Objective To explore the function of Dock2 in the host′s adaptive immunity against C. roden⁃ tium infection，and study the relationship between the changes of lymphocytes and bacterial clearance in the late stage of C. rodentium infection. Methods WT and Dock2⁃/⁃mice were intragastrically infected with C. rodentium to observe the infection within 21 days. ELISA was used to detected IFN⁃γ，TNF⁃α，KC，MCP⁃1 and MIP⁃2 in the sera of mice during 21 days，the protein expression levels of IL⁃6 and IL⁃17，and the levels of specific antibodies IgM，IgG，IgG1，IgG2b，IgG2c and IgG3；flow cytometry was used to detect T lymphocytes and thymocytes. The T lymphocytes isolated from WT and Dock2-/- were injected into the TCRa-/- mice by tail veins，and the levels of IgG，IgG1，IgG2b，IgG2c，IgG3，IgA and IgM were detected by ELISA. Sera of WT mice at D0 and D21 after infection were injected into the tail veins of Dock2-/- mice followed by infection，and the survival rates were recorded. Results：After C.rodentium infection，Dock2-/- mice had much more production of pro⁃ inflammatory cytokines and macrophage/neutrophil infiltration than WT mice. The mechanism of bacterial clearance disorder caused by Dock2 deletion after C. rodentium infection may be associated with the T⁃cell and B⁃cell deficiency，and reduced serum antigen⁃specific IgG antibody in Dock2-/- mice. Consistently ，T cell transfer and serum transfer has inhibitory effects on C.rodentium⁃induced colitis. Conclusion Dock2 was required for host bacterial clearance after C.roden⁃tium infection.  

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