EffektorTceller

EffektorTceller, commonly referred to as effector T cells, are a functional stage of T lymphocytes that actively participate in the immune response after activation. They originate from naive T cells that encounter their specific antigen in the context of major histocompatibility complex (MHC) presentation and receive necessary co-stimulatory signals, leading to clonal expansion and differentiation.

Effector T cells include cytotoxic CD8+ T cells, which kill infected or malignant cells through mechanisms such as perforin and granzymes, and helper CD4+ T cells, which differentiate into effector subsets like Th1, Th2, and Th17 to coordinate immune responses via cytokine secretion. Regulatory T cells are not considered effector cells. The effector functions encompass direct cytolysis, production of cytokines (for example IFN-γ, TNF-α, IL-2), and provision of help to B cells and macrophages to amplify the immune response.

Activation of effector T cells requires T cell receptor engagement with antigen-MHC complexes on antigen-presenting cells, together with co-stimulatory signals such as CD28-B7 interaction. The cytokine milieu influences differentiation into specific effector lineages, with transcription factors including T-bet (Th1), GATA3 (Th2), and RORγt (Th17) guiding fate; cytotoxic function in CD8+ cells is supported by factors such as Eomesodermin.

Effector T cells have a finite lifespan: after antigen clearance, most undergo contraction and die by apoptosis, while a fraction persists as memory T cells for faster responses upon re-exposure. Clinically, robust effector T cell responses are central to vaccines, antiviral immunity, and cancer immunotherapy.