CD8A and cancer: Hamano et al. showed that the efficient priming of Th cell responses by APCs in vivo was IC dependent.55 In cancer antitumor vaccine studies, IC-loaded dendritic cells (DCs) were found superior to soluble ICs.56 Circulating antibodies were shown to enhance systemic cross priming by delivery of antigens to DCs57 and ICs not only induced DC maturation in vitro, but also enabled DCs to prime peptide-specific CD8+ CTLs in vivo.58 These dual roles in enhancement of Ag uptake and activation of DCs and in priming of CD8+ CTL responses to exogenous antigens, resulted in a “license to kill” function.