Helper T-cell responses elicited by Der p 1–pulsed dendritic cells and recombinant IL-12 in atopic and healthy subjects

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Abstract

Background:

Environmental allergens, such as Dermatophagoides pteronyssinus group 1 antigen (Der p 1), induce TH2-type responses in atopic patients, whereas healthy individuals have TH1-type responses to the same antigens. Because of their efficient synthesis of IL-12, dendritic cells (DCs) are potent inducers of TH1-type immune responses.

Objective:

We sought to determine whether DCs would skew allergen-specific TH2-type responses from atopic individuals.

Methods:

Purified CD4+ T cells from healthy donors or atopic individuals were cultured in the absence or presence of recombinant (r)IL-12 with DCs derived from PBMCs and pulsed with Der p 1. Supernatants of DC-T cell cocultures were assayed by ELISA for IL-5 and IFN-γ.

Results:

A TH1-type response developed in purified CD4+ T cells from healthy donors in response to Der p 1–pulsed DCs, as indicated by high levels of IFN-γ in culture supernatants. In contrast, CD4+ T cells from atopic donors displayed a TH2-type profile characterized by high levels of IL-5 and low levels of IFN-γ. The addition of rIL-12 (10 ng/mL) to DC-T cell cocultures resulted in the induction of IFN-γ secretion by Der p 1–specific CD4+ T cells from atopic patients, whereas their production of IL-5 was not inhibited. Using flow cytometry after intracytoplasmic staining, we found that IFN-γ and IL-5 were secreted by distinct CD4+ T-cell subpopulations.

Conclusion:

The cytokine profile of Der p 1–specific TH2-like cells from atopic individuals is maintained when the allergen is presented by DCs, even in the presence of exogenous rIL-12.

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