IFN-α Suppresses Myeloid Cytokine Production, Impairing IL-12 Production and the Ability to Support T-Cell Proliferation

Abstract Background Interferon-α (IFN-α) can suppress production of T-cell polarizing cytokines or induce inhibitory antigen-presenting cells that suppress T-cell activation. Previous studies showed that IFN-α therapy fails to boost virus-specific T-cell immunity in patients with chronic hepatitis B virus infection. Our aim was to determine whether IFN-α exposure alters human antigen-presenting cell function in vivo. Methods We investigated the immunomodulatory effects using peripheral blood mononuclear cells from healthy donors exposed to IFN-α and chronic hepatitis B (CHB) patients starting IFN-α therapy. Results IFN-α increased HLA-DR, CD80, CD86, and PD-L1 expression on healthy donor monocytes. In contrast to the activated phenotype, IFN-α inhibited Toll-like receptor-induced cytokine production and monocyte-induced T-cell proliferation. In CHB patients, peg-IFN treatment induced an interferon-stimulated gene signature in monocytes and increased HLA-DR, CD80, CD86, and PD-L1 expression. As early as 3 days after CHB patients started treatment, IFN-α inhibited monocyte cytokine production and T-cell stimulation ex vivo. IFN-α-mediated inhibition of IL-12 production, rather than inhibitory receptor expression, was responsible for inhibition of T-cell proliferation. Addition of IL-12 restored T-cell proliferation to baseline levels. Conclusions Understanding how professional antigen-presenting cells respond to immunomodulation is important for both new innate and adaptive-targeted immunotherapies. Clinical Trials Registration NCT00962871.