Exogenous IL-2 Induces FoxP3+ Th17 Cells In Vivo in Melanoma Patients

Abstract

Introduction Th17 cells represent a distinct subset of CD4+ effector T cells with potent pathogenic qualities, capable of directly mediating tumor cell destruction. IL-2 has frequently been shown to have a negative impact on Th17 differentiation while supporting regulatory T cell (FoxP3+CD4+, TREG) growth and development in both in vitro models and in vivo animal models. We investigated the effect of in vivo IL-2 on both the Th17 and FoxP3+CD4+ T cell compartments in a human model of cancer. Methods High-dose IL-2 (HDIL-2) was administered at a dose of 720,000 IU/kg to patients with melanoma (n=7) and peripheral blood was collected at baseline and at 24, 48, 72, and 96 hours post-treatment. PBMCs were isolated and underwent intracellular cytokine and extracellular receptor staining for flow cytometry. Results We report that HDIL-2 increased both frequencies and absolute numbers of Th17 cells on day 4 of treatment. The administration of HDIL-2 to patients with melanoma increased IL-6 production by peripheral immune cells, a cytokine vital in the downregulation of FoxP3 expression and expansion of the Th17 cell population. Furthermore, we demonstrated that FoxP3+CD4+ T cells express IL-17 in patients with melanoma undergoing HDIL-2 therapy. Conclusions Taken together, our findings indicate that HDIL-2 combined with the conditions of malignancy create an immune environment supportive of Th17 differentiation and that expansion of this compartment may occur via the trans-differentiation of IL-17-secreting FoxP3+CD4+ T cells.

Advances in Proteomic Techniques for Cytokine Analysis: Focus on Melanoma Research

“…The most frequently studied cytokine producing cells are T-lymphocytes [ 190 ] but also other cell populations, including basophils [ 191 ], neutrophils [ 192 , 193 ], NK cells [ 194 ], monocytes [ 192 ] and mast cells [ 195 ] are investigated. In melanoma, flow cytometry was applied to study mechanisms of effects of immunotherapies, such as a PD-1 protein blockade by monoclonal antibodies pembrolizumab or nivolumab [ 196 , 197 , 198 ], CTLA-4 blockade with ipilimumab [ 198 , 199 , 200 , 201 ] or high-dose IL-2 therapy [ 202 , 203 ]. Intracellular cytokine staining can be used to monitor tumour antigen-specific T-cell functions [ 204 , 205 , 206 ] in the search for anti-tumour competent cytotoxic T-cells.…”

Targeting regulatory T cells for immunotherapy in melanoma

“…Tregs produce immunosuppressive cytokines to inhibit effector T cell expansion and release cell membrane soluble mediators, granzymes and perforin, to induce effector T cell apoptosis [107][108][109]. Tregs also consume IL-2 by expressing high level of CD25 (IL-2 receptor) to inhibit the proliferation of effector T cells [110].…”