CD4(+) Lymphoid Tissue-Inducer
Cells Promote Innate Immunity in the Gut
Sonnenberg GF, Monticelli LA, Elloso MM, Fouser LA, Artis
Immunity 34(1):122-34, 2011
Fetal CD4(+) lymphoid tissue inducer (LTi) cells play a
critical role in the development of lymphoid tissues. Recent
studies identified that LTi cells persist in adults and are
related to a heterogeneous population of innate lymphoid
cells that have been implicated in inflammatory responses.
However, whether LTi cells contribute to protective immunity
remains poorly defined. We demonstrate that after infection
with Citrobacter rodentium, CD4(+) LTi cells were a dominant
source of interleukin-22 (IL-22) early during infection.
Infection-induced CD4(+) LTi cell responses were IL-23 dependent,
and ablation of IL-23 impaired innate immunity. Further,
depletion of CD4(+) LTi cells abrogated infection-induced
expression of IL-22 and antimicrobial peptides, resulting
in exacerbated host mortality. LTi cells were also found
to be essential for host protective immunity in lymphocyte-replete
hosts. Collectively these data demonstrate that adult CD4(+)
LTi cells are a critical source of IL-22 and identify a previously
unrecognized function for CD4(+) LTi cells in promoting innate
immunity in the intestine.