Development of IL-17-mediated delayed-type hypersensitivity is not affected by down-regulation of IL-25 expression.
BACKGROUND
IL-25, which is a member of the IL-17 family, induces Th2 cell differentiation and Th2 cytokine production, contributing to induction of Th2-type immune responses and diseases, as a result of which it suppresses Th1- and Th17-type immune responses.


METHODS
To elucidate the role of IL-25 in the pathogenesis of IL-17-mediated delayed-type hypersensitivity (DTH), IL-25-deficient mice were sensitized with methylated BSA (mBSA), and then a DTH reaction was induced by mBSA challenge. mBSA-specific T-cell induction was assessed on the basis of cell proliferation and cytokine production. The DTH reaction was evaluated on the basis of tissue swelling, histology and inflammatory mediator expression.


RESULTS
IL-25 expression was markedly reduced in local DTH lesions. However, mBSA-specific Th1, Th2 and Th17 cell induction, and the mBSA-induced DTH reaction were comparable in IL-25-deficient and wild-type mice.


CONCLUSIONS
IL-25 is not essential for differentiation of Th1, Th2 and Th17 cells in the sensitization phase or induction of local inflammation in the elicitation phase of the mBSA-induced DTH reaction.
Ishii
Akina
A
Department of Allergy and Immunology, National Research Institute for Child Health and Development, Tokyo, Japan.
Oboki
Keisuke
K
Nambu
Aya
A
Morita
Hideaki
H
Ohno
Tatsukuni
T
Kajiwara
Naoki
N
Arae
Ken
K
Sudo
Hajime
H
Okumura
Ko
K
Saito
Hirohisa
H
Nakae
Susumu
S
D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D015536:Down-Regulation; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007114:Immunization; D020381:Interleukin-17 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D058504:Th17 Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology
C486701:IL25 protein, human; D020381:Interleukin-17