IgG from atopic dermatitis patients induces IL‐17 and IL‐10 production in infant intrathymic TCD4 and TCD8 cells

Introduction Our group recently demonstrated that IgG modulates αβT cell cytokine production during the maturation process in the human thymus. The effects of this modulation are IgG repertoire dependent and can exert a systemic and long‐term impact. Objective To investigate whether IgG from atopic dermatitis (AD) patients can modulate cytokine production of infant intrathymic TCD4 and TCD8 cells in vitro. Methods Thymic tissues were obtained from newborn children from nonatopic mothers, and thymocytes were cultured for 6 days with purified IgG from AD patients or with intravenous immunoglobulin (IVIG) or mock conditions as controls. Cells were gated as double positive T cells (TDP−CD4+CD8+), TCD4 cells (CD4+CD8−), or TCD8 cells (CD4−CD8+), and intracellular levels of IL‐17A, IFN‐γ, TNF‐α, IL‐4, IL‐10, and TGF‐β were evaluated by flow cytometry. Results Compared to mock and IVIG culture conditions, IgG of AD individuals induced in vitro intracellular production of IL‐17 and IL‐10 by intrathymic TDP, TCD4, and TCD8 cells of infants. TGF‐β was also detected at a higher frequency in response to AD IgG in TDP and TCD8 cells compared to mock and IVIG cultured conditions. An opposite effect was detected upon IFN‐γ production in TCD4 cells, such that AD IgG reduced IFN‐γ production compared to production under mock conditions but not under IVIG conditions. Conclusion IgG of AD patients can stimulate cytokine production in infant thymocytes and thus resembles the peripheral profile observed in adults. These findings suggest a novel mechanism that can contribute to AD pathogenesis.