Induction of Bet-specific iTreg from birch-pollen allergic
patients with associated hazelnut allergy by autologous IL-10 DC
As previously demonstrated by us, human IL-10 DC induce iTreg with a
high capacity to suppress T cell responses in an antigen-specific
manner.35,38,42,43 In this study, we wanted to
investigate whether these tolerogenic IL-10 DC are able to induce an
allergen-specific as well as cross-reactive tolerance in patients
suffering from a pollen (birch, Bet v 1) and associated food (hazelnut,
Cor a 1) allergy (for patients´ details see Supplementary Table 1). For
this purpose, we used our previously established in vitro model
with human DC to analyze allergen-specific and cross-reactive T cell
responses.12
IL-10 DC obtained from birch pollen allergic patients with associated
hazelnut allergy were loaded with Bet or left unloaded (IL-10
DCBet/IL-10 DC0) and cocultured with
autologous CD4+ T cells to induce Bet-specific or
control iTreg, respectively
(iTregBet/iTreg0). In addition, mDC
(mDCBet/mDC0) were used to generate
Bet-specific and non-specific Teff
(TeffBet/Teff0) as controls (see
Methods, Supplementary Methods and Supplementary Figure 1).
After primary culture, TeffBet exhibited a significantly
increased proliferative capacity compared to Teff0,
demonstrating an allergen (Bet)-specific T cell response (Figure 1A). In
contrast, stimulation with IL-10 DC0 or
IL-10DCBet resulted in a significantly reduced T cell
proliferation of both iTreg0 and
iTregBet.
In line with the data of allergen-specific T cell proliferation,
analysis of cytokine production after primary culture revealed
significantly increased levels of TH2 cytokines (IL-5,
IL-9 and IL-13) and of IL-2 (T cell activation) in supernatants of
mDCBet activated TeffBet compared to
control Teff0, demonstrating highly stimulated
Bet-specific Teff (Figure 1B-E). In contrast, supernatants of iTreg
primed by IL-10 DC0 or IL-10 DCBet,
respectively, exhibited reduced amounts of TH2 cytokines
in comparison to Bet-specific control Teff, confirming the diminished
activity of iTreg after primary culture. However, we observed very high
IL-10 concentrations produced by iTregBet compared to
control TeffBet/Teff0 as well as to
iTreg0, suggesting the immunosuppressive cytokine IL-10
as mediator of allergen-specific iTreg suppressor function (Figure 1F).