T helper 1 cell-mediated immune response against Bartonella henselae in mouse infection model

초록

Bartonella henselae is an intracellular Gram-negative organism causing common zoonosis, including cat scratch fever. After infection, T helper 1 cell-mediated immune response against B. henselae is expected to develop, resulting in elimination of bacteria. Immune responses against B. henselae were investigated in mouse model after intraperitoneal infection of BALB/c mouse. Normal spleen cells infected with 2x107 CFU of B. henselae were incubated for 3 days and the secreted cytokines were measured by ELISA. The infected spleen cells secreted large amount of IFN-gamma and IL-10, but not IL-4. Next, we infected BALB/c mice for 5 days and their spleen cells were harvested. These immune spleen cells were activated in vitro with the lysate of B. henselae and the number of cytokine-secreting cells was measured using ELISPOT. The number of cells secreting IL-4 was significantly lower than that of cells secreting IFN-gamma. In addition, the number of spleen cells secreting IL-10 increased after infection with B. henselae. These results indicate that the activation of T helper 1 cell-mediated immune responses play an important role in the control of B. henselae. However, a strong IL-10 response was simultaneously induced by the bacterium. A balance between the cell-mediated immune responses and the immune suppression of IL-10 response might alter the course and outcome of disease by B. henselae infection.