Cell-mediated immunity plays a crucial role in the control of many infectious 
diseases, necessitating the need for adjuvants that can augment cellular immune 
responses elicited by vaccines. It is well established that protection against 
one such disease, malaria, requires strong CD8(+) T cell responses targeted 
against the liver stages of the causative agent, Plasmodium spp. In this report 
we show that the dendritic cell-specific chemokine, dendritic cell-derived CC 
chemokine 1 (DC-CK1), which is produced in humans and acts on naive lymphocytes, 
can enhance Ag-specific CD8(+) T cell responses when coadministered with either 
irradiated Plasmodium yoelii sporozoites or a recombinant adenovirus expressing 
the P. yoelii circumsporozoite protein in mice. We further show that these 
enhanced T cell responses result in increased protection to malaria in immunized 
mice challenged with live P. yoelii sporozoites, revealing an adjuvant activity 
for DC-CK1. DC-CK1 appears to act preferentially on naive mouse lymphocytes, and 
its adjuvant effect requires IL-12, but not IFN-gamma or CD40. Overall, our 
results show for the first time an in vivo role for DC-CK1 in the establishment 
of primary T cell responses and indicate the potential of this chemokine as an 
adjuvant for vaccines against malaria as well as other diseases in which 
cellular immune responses are important.