Inefficient antigen presentation via the IgA Fc receptor (FcαRI) on dendritic cells

Dendritic cells (DC) are professional antigen presenting cells that can induce and regulate adaptive immune responses. For that reason, DC are attractive candidates for vaccination strategies. Recently, expression of the IgA Fc receptor (Fc alpha RI, C1389) was observed on DC, which activation led to DC maturation. We have investigated the potential of DC Fc alpha RI as a target molecule for vaccination against cancer. Fc alpha RI expression was observed on human blood myeloid DC. Furthermore, expression of Fc alpha RI was low on immature DC, cultured from either human monocytes or Fc alpha RI transgenic (Tg) mouse bone marrow cells. Addition of TNF-alpha to culture regimes of both human and mouse DC led to more semi-mature DC, on which Fc alpha RI expression was slightly upregulated. Fc alpha RI on both human and Fc alpha RI Tg mouse DC was internalized after receptor crosslinking. Antigen presentation, measured in Fc alpha RI Tg mouse DC, was however minimal. As antigen presentation is crucial to elicit effective T cell responses, these data suggest that targeting of DC Fc alpha RI is not optimal for DC vaccination strategies. (c) 2006 Elsevier GmbH. All rights reserved.