CXC chemokines that lack the glutamine-leucine-arginine (ELR) motif, including interferon (IFN)-inducible protein 10 (IP-10 or CXCL10), have been shown to mediate the generation of type 1 immune responses. In this study, we found that the intrapulmonary transient transgenic expression of murine IP-10 in mice using adenoviral gene transfer resulted in the early accumulation of neutrophils, natural killer (NK) cells, and NK T cells within the lung, followed by the delayed accumulation of CD4⁺ T cells. Adenovirus-mediated transgenic expression of IP-10 also resulted in selective activation of mononuclear cells, including γδ-T cells and NK cells, as manifest by CD69 expression or induction of cell-associated IFN-γ. Importantly, the intratracheal (i.t.) administration of a control human type 5 adenovirus also caused significant accumulation of NK, NK T, and CD4⁺ T cells, which was maximal at 7 days post vector administration and was associated with the induction of IP-10. Neutralization of endogenous IP-10 in animals receiving control adenovirus resulted in decreases in the numbers of NK, CD4⁺, and CD8⁺ T cells. These results indicate that IP-10 can direct the accumulation and activation of neutrophils and selected mononuclear cells to the lung and that adenovirusinduced IP-10 contributes to lung inflammatory cell recruitment/activation observed in response to adenoviral vectors used for gene therapy.