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Precocious Interleukin 21 Expression in Naive Mice Identifies a Natural Helper Cell Population in Autoimmune Disease

Year: 2017

Type: article

Abstract: Interleukin 21 (IL-21) plays key roles in humoral immunity and autoimmune diseases. It is known to function in mature CD4 + T follicular B cell helper (T FH ) cells, but its potential involvement in early T cell ontogeny is unclear. Here, we find that a significant population of newly activated thymic and peripheral CD4 + T cells functionally expresses IL-21 soon after birth. This naturally occurring population, termed natural (n)T H 21 cells, exhibits considerable similarity to mature T FH cells. nT H 21 cells originating and activated in the thymus are strictly dependent on autoimmune regulator (AIRE) and express high levels of NUR77, consistent with a bias toward self-reactivity. Their activation/expansion in the periphery requires gut microbiota and is held in check by FoxP3 + T REG cells. nT H 21 cells are the major thymic and peripheral populations of IL-21 + cells to expand in an IL-21-dependent humoral autoimmune disease. These studies link IL-21 to T cell ontogeny, self-reactivity, and humoral autoimmunity.

Source: Cell Reports

DOI: 10.1016/j.celrep.2017.09.036