Differential pathways regulating innate and adaptive antitumor immune responses by particulate and soluble yeast-derived ?-glucans.
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ABSTRACT: ?-glucans have been reported to function as a potent adjuvant to stimulate innate and adaptive immune responses. However, ?-glucans from different sources are differential in their structure, conformation, and thus biologic activity. Different preparations of ?-glucans, soluble versus particulate, further complicate their mechanism of action. Here we show that yeast-derived particulate ?-glucan activated dendritic cells (DCs) and macrophages via a C-type lectin receptor dectin-1 pathway. Activated DCs by particulate ?-glucan promoted Th1 and cytotoxic T-lymphocyte priming and differentiation in vitro. Treatment of orally administered yeast-derived particulate ?-glucan elicited potent antitumor immune responses and drastically down-regulated immunosuppressive cells, leading to the delayed tumor progression. Deficiency of the dectin-1 receptor completely abrogated particulate ?-glucan-mediated antitumor effects. In contrast, yeast-derived soluble ?-glucan bound to DCs and macrophages independent of the dectin-1 receptor and did not activate DCs. Soluble ?-glucan alone had no therapeutic effect but significantly augmented antitumor monoclonal antibody-mediated therapeutic efficacy via a complement activation pathway but independent of dectin-1 receptor. These findings reveal the importance of different preparations of ?-glucans in the adjuvant therapy and allow for the rational design of immunotherapeutic protocols usable in clinical trials.
SUBMITTER: Qi C
PROVIDER: S-EPMC3128477 | biostudies-literature | 2011 Jun
REPOSITORIES: biostudies-literature
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