Abstract
BackgroundSpecific subcutaneous immunotherapy (SCIT) can achieve long-term remission in patients with allergic rhinitis (AR) through complex and still unknown mechanisms. The aim of this study is to evaluate the effect of SCIT over CD16+ and CD16− monocytes, myeloid (mDCs) and plasmacytoid dendritic cells (pDCs) in patients with AR, comparatively to pharmacological standard treatment (non-SIT).MethodsThe relative frequency and absolute number of monocytes and DC subsets, the frequency of these cells producing TNFα after in vitro stimulation with Dermatophagoides pteronyssinus (Dpt) extract, and the expression levels of receptor-bound IgE or IgG were assessed by flow cytometry, in peripheral blood samples from 23 healthy individuals (HG) and 43 participants with AR mono-sensitized to Dpt; 10 with non-SIT treatment and 33 under SCIT, just before (SCIT-T0) and 4 h after administration (SCIT-T4). Moreover, IFNα mRNA expression was evaluated in purified pDCs, by qRT-PCR.ResultsAfter SCIT administration we observed a strong decrease of circulating pDCs, although accompanied by higher levels of IFNα mRNA expression, and an increase of circulating CD16+ monocytes. AR participants under SCIT exhibited a higher expression of receptor-bound IgE in all cell populations that expressed the high affinity receptor for IgE (FcεRI) and a higher frequency of CD16+ monocytes producing TNFα. Conversely, we observed a decrease in the frequency of mDCs producing TNFα in AR under SCIT, similar to the observed in the control group.ConclusionsSCIT seems to induce numeric, phenotypic, and functional changes in circulating monocytes and dendritic cells, contributing at least in part to the well described immunological alterations induced by this type of immunotherapy.
Highlights
Specific subcutaneous immunotherapy (SCIT) can achieve long-term remission in patients with allergic rhinitis (AR) through complex and still unknown mechanisms
Relative and absolute quantification of peripheral blood monocytes and dendritic cells (DCs) subpopulations After 4 h of SCIT administration we observed a strong depletion of plasmacytoid dendritic cells (pDCs) (SCIT-T4), though the percentage and absolute values of these cells were higher in AR participants independently of the therapeutic protocol, when compared with the control group (HG)
MDCs were decreased in AR participants under conventional pharmacological treatment, whereas SCIT seemed to increase the percentage and absolute value of these cells to similar levels observed in the HG (Table 2)
Summary
Specific subcutaneous immunotherapy (SCIT) can achieve long-term remission in patients with allergic rhinitis (AR) through complex and still unknown mechanisms. The aim of this study is to evaluate the effect of SCIT over CD16+ and CD16− monocytes, myeloid (mDCs) and plasmacytoid dendritic cells (pDCs) in patients with AR, comparatively to pharmacological standard treatment (non-SIT). Antigen-presenting cells (APCs), especially dendritic cells (DCs), are known to play a fundamental role in the onset of allergic sensitization and in the repeated activation of Th2-mediated responses. FcεRI can be found in the cell membrane of DCs and in a small subpopulation of monocytes. Allergen specific immunotherapy (SIT) is far the only treatment option that changes the immunologic mechanism of allergy thereby modifying the natural course of the disease with the potential for long-term benefits as well as preventing sensitizations to new allergens. SIT consists in allergen administration to decrease sensitivity to the allergen; typically, through sublingual delivery (SLIT) or subcutaneous injections (SCIT)
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