Simplified assay for enrichment of primed human Th17 and Tc17 lymphocytes from peripheral blood

Abstract

Background: Interleukin-17A (IL-17A) is a potent pro-inflammatory cytokine that has been implicated in the pathogenesis of various autoimmune diseases. The production of IL-17A is commonly associated with subsets of CD4+ T cells (Th17) and CD8+ T cells (Tc17). Identifying these subsets based on intracellular expression of IL-17 or transcription factor RORC precludes isolation of viable Th17 and Tc17 cells and there by limits studies involving cell-cell interaction or cellular functions. Therefore, identifying surface markers that can help in identifying and enriching these cells is important. Results: We used MCAM as a surrogate marker to identify in vivo committed human Th17 and Tc17 subsets. By employing high-speed fluorescence activated cell sorting, we enriched IL-17A-producing subsets from human specimens without the need for in vitro polarization using exogenous cytokines. These subsets can be investigated, following sorting, using a variety of methods such as ELISA, ex vivo functional assays and next generation sequencing to gain insights into the role of human Th17 and Tc17 in health and disease. Conclusion: We here demonstrate that both CD4+ T cells (Th17) and CD8+ T cells (Tc17) cell populations can be identified based on the surface expression of melanoma cell adhesion molecule (MCAM or CD146).