CD4-positive T helper 17 cell (Th17 cell)

CD4-positive T helper 17 cells (Th17 cells) are a specialized subset of CD4+ T lymphocytes defined by their production of the cytokine interleukin 17A (IL‑17A), as well as other cytokines such as IL‑17F, IL‑21, and IL‑22[1][2][6]. They differentiate from naïve CD4+ T cells in response to specific cytokine environments—primarily involving transforming growth factor beta (TGFβ) with interleukin 6 or interleukin 21—and require the transcription factor RORγt for lineage commitment[1][7]. Th17 cells play a critical role in host defense against extracellular bacteria and fungi at mucosal and epithelial barriers by recruiting neutrophils and promoting inflammation[1][6][8]. Aberrant activation or dysregulation of Th17 responses is implicated in the pathogenesis of several autoimmune diseases due to their potent pro-inflammatory effects[5]. Additionally, they contribute to tissue-specific inflammatory responses and have been shown to participate in antitumor immunity. In infectious diseases such as HIV infection, Th17 cells are preferentially targeted by the virus and constitute an important component of viral reservoirs during antiretroviral therapy[7]. While "Th17" refers specifically to this functional immune cell subset rather than a single molecular target like a receptor or enzyme—and thus is not itself considered a direct therapeutic target—the pathways regulating its differentiation or effector functions are actively pursued for drug development. For example, drugs targeting the cytokines produced by these cells (such as anti–IL‑17 antibodies) are used therapeutically in autoimmune conditions. Note: The entry "CD4+ T cell Th17 subset" describes an immune cell population, not a discrete molecule/receptor/target. Therefore, is_target is false, and is_incorrect is true, because it does not refer to a canonical molecular target but rather an immunological phenotype/subset.

Other names

T helper 17 cellTh17 subsetCD4+ Th17 cell