[T(H)17 lymphocytes: induction, phenotype, functions, and implications in human disease and therapy].

Differentiation of naive CD4(+) T helper (T(H)) cells is a major step of the adaptative immune response. When activated by pathogens in a specific cytokine environment, CD4(+) T cells differentiate into different subsets of T(H) cells with specific effector functions. T(H)1 lymphocytes orchestrate cellular immune response by producing interferon-γ and stimulating cytotoxic cells whereas T(H)2 cells orchestrate humoral immune response by producing interleukin-4 (IL-4), IL-5 and IL-10, leading to immunoglobulin production. Conversely, regulatory T cells (Treg) are capable of inhibiting immune response. Recently discovered, T(H)17 cells are characterized by their ability to produce IL-17 and play an important role in anti-infectious and inflammatory immune responses. This review focuses on present knowledge about T(H)17 cells: their induction, phenotype, functions, implications in host defense and human disease, and their potential to represent possible therapeutic targets.