CpG oligodeoxynucleotides enhance FcγRI-mediated cross presentation by dendritic cells

Abstract

Dendritic cells (DC) can trigger naive CD8+ T cell responses by their capacity to cross-present exogenous antigens via the major histocompatibility complex class I pathway. The myeloid class I IgG receptor, FcγRI (CD64), is expressed on DC, and in vivo targeting of antigens to FcγRI induces strong humoral and cellular immune responses. We studied the capacity of human FcγRI (hFcγRI) to facilitate DC-mediated cross presentation and T cell activation, and assessed the effect of CpG oligodeoxynucleotides on this process. We generated hFcγRI expressing immature DC from hFcγRI transgenic and immature DC from non-transgenic mice. Antigens were targeted to Fcγ receptors as ovalbumin immune complexes, or selectively to hFcγRI via ovalbumin-CD64 mAb fusion proteins. Co-incubation of immature DC with CpG ODN led to markedly increased MHC class I presentation of FcγR-targeted antigens. When OVA was selectively targeted to hFcγRI, few differences were observed between Tg and NTg DC. However, upon co-incubation with CpG ODN, hFcγRI-triggered cross presentation was enhanced. These results document the capacity of hFcγRI on DC to trigger cross presentation via MHC class I upon co-culture with CpG ODN. © 2004 The Japanese Society for Immunology.