Targeting the neonatal Fc receptor for antigen delivery using engineered Fc fragments

Wentao Mi, Sylvia Wanjie, Su Tang Lo, Zhuo Gan, Beatrix Pickl-Herk, Raimund J. Ober, E. Sally Ward

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


The development of approaches for Ag delivery to the appropriate subcellular compartments of APCs and the optimization of Ag persistence are both of central relevance for the induction of protective immunity or tolerance. The expression of the neonatal Fc receptor, FcRn, in APCs and its localization to the endosomal system suggest that it might serve as a target for Ag delivery using engineered Fc fragment-epitope fusions. The impact of FcRn binding characteristics of an Fc fragment on in vivo persistence allows this property to also be modulated. We have therefore generated recombinant Fc (mouse IgG1-derived) fusions containing the N-terminal epitope of myelin basic protein that is associated with experimental autoimmune encephalomyelitis in H-2 u mice. The Fc fragments have distinct binding properties for FcRn that result in differences in intracellular trafficking and in vivo half-lives, allowing the impact of these characteristics on CD4+ T cell responses to be evaluated. To dissect the relative roles of FcRn and the "classical" FcγRs in Ag delivery, analogous aglycosylated Fc-MBP fusions have been generated. We show that engineered Fc fragments with increased affinities for FcRn at pH 6.0 -7.4 are more effective in delivering Ag to FcRn-expressing APCs in vitro relative to their lower affinity counterparts. However, higher affinity of the FcRn-Fc interaction at near neutral pH results in decreased in vivo persistence. The trade-off between improved FcRn targeting efficiency and lower half-life becomes apparent during analyses of T cell proliferative responses in mice, particularly when Fc-MBP fusions with both FcRn and FcγR binding activity are used.

Original languageEnglish (US)
Pages (from-to)7550-7561
Number of pages12
JournalJournal of Immunology
Issue number11
StatePublished - Dec 1 2009

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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