Early gene expression of NK cell-activating chemokines in mice resistant to Leishmania major

Susceptibility of mice to Leishmania major is associated with an insufficie nt NK cell-mediated innate immune response. We analyzed the expression of N K cell-activating chemokines in vivo during the first days of infection in resistant and susceptible mice. The mRNA expression of gamma interferon-ind ucible protein 10 (IP-10), monocyte chemoattractant protein 1 (MCP-1), and lymphotactin was upregulated 1 day after infection in the draining lymph no des of resistant C57BL/6 mice but not in those of susceptible BALB/c mice. In vivo local treatment of BALB/c mice with recombinant IP-10 shortly after infection resulted in an enhanced NK cell activity in the draining lymph n ode. The data suggest that although the recruitment of NK cells is normal i n susceptible mice, the lack of NK cell-activating chemokines is a factor r esulting in a suboptimal NK cell-mediated defense.