An investigation into IgE-facilitated allergen recognition and presentation by human dendritic cells

Abstract

Background: Allergen recognition by dendritic cells (DCs) is a key event in the allergic cascade leading to production of IgE antibodies. C-type lectins, such as the mannose receptor and DC-SIGN, were recently shown to play an important role in the uptake of the house dust mite glycoallergen Der p 1 by DCs. In addition to mannose receptor (MR) and DC-SIGN the high and low affinity IgE receptors, namely Fcε{lunate}RI and Fcε{lunate}RII (CD23), respectively, have been shown to be involved in allergen uptake and presentation by DCs.Objectives: This study aims at understanding the extent to which IgE- and IgG-facilitated Der p 1 uptake by DCs influence T cell polarisation and in particular potential bias in favour of Th2. We have addressed this issue by using two chimaeric monoclonal antibodies produced in our laboratory and directed against a previously defined epitope on Der p 1, namely human IgE 2C7 and IgG1 2C7.Results: Flow cytometry was used to establish the expression patterns of IgE (Fcε{lunate}RI and Fcε{lunate}RII) and IgG (FcγRI) receptors in relation to MR on DCs. The impact of Fcε{lunate}RI, Fcε{lunate}RII, FcγRI and mannose receptor mediated allergen uptake on Th1/Th2 cell differentiation was investigated using DC/T cell co-culture experiments. Myeloid DCs showed high levels of Fcε{lunate}RI and FcγRI expression, but low levels of CD23 and MR, and this has therefore enabled us to assess the role of IgE and IgG-facilitated allergen presentation in T cell polarisation with minimal interference by CD23 and MR. Our data demonstrate that DCs that have taken up Der p 1 via surface IgE support a Th2 response. However, no such effect was demonstrable via surface IgG.Conclusions: IgE bound to its high affinity receptor plays an important role in Der p 1 uptake and processing by peripheral blood DCs and in Th2 polarisation of T cells. © 2013 Sharquie et al.; licensee BioMed Central Ltd.