Monocyte-derived dendritic cells (DC) are currently used in clinical trials as carders of anti-cancer vaccines. As it has been shown that DC developing and maturing in different conditions show strong differences in their abilities to produce cytokines and to induce Th1, Th2, and CTL responses, it is likely that DC will also differ in their ability to exert antitumor therapeutic effect. Despite extensive in vitro characterization of distinct functional subsets of DC, their ability to induce immune responses of different character and magnitude has not been tested in vivo. We propose to develop a model system for evaluating and optimizing myeloid and plasmacytoid DC function in rhesus macaques. Based on previous results, we hypothesize that polarized myeloid DC1, grown in GM-CSF and IL-4 and which in vitro produce high levels of IL-12 and preferentially induce Th1 and CTL responses, will prove to be the most potent DC for stimulating Th1 and CTL responses in vivo. However, plasmacytoid DC have also been shown to induce Th1 and CTL responses, as have DC cultured in GM-CSF and IL-15. We propose to test the efficacy of DC generated in different protocols and at different stages of maturation, polarized by different sets of cytokines, as well as exposed to multiple Forms of antigen, to induce different classes of immune responses in vitro and in vivo. We will first develop protocols for generating rhesus DC, loading them with antigens, and inducing polarized phenotypes in vitro. The phenotype and functional capacities of these cells, including cytokines produced, will be characterized extensively. We will next test the different types of DC for efficient localization in T cell areas of lymph nodes after intranodal injection. Finally, we will test in vivo the ability of different DC types to stimulate polarized CD4 T cell responses to antigens and to stimulate CD8 T cells responses. Immunization strategies that provoke strong Th1-type responses will potentially be used for clinical trials being performed in other projects within this P01, and in future studies.
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