Interleukin-15 may be responsible for early activation of intestinal intraepithelial lymphocytes after oral infection with Listeria monocytogenes in rats.
Exogenous interleukin-15 (IL-15) stimulates intestinal intraepithelial lymphocytes (i-IEL) from mice to proliferate and produce gamma interferon (IFN-gamma) in vitro. To determine whether endogenous IL-15 is involved in activation of i-IEL during intestinal infection, we examined IL-15 synthesis by intestinal epithelial cells (i-EC) after infection with Listeria monocytogenes in rats. In in vitro experiments, invasion of L. monocytogenes into IEC-6 cells, a rat small intestine epithelial cell line, evidently induced IL-15 mRNA expression coincident with nuclear factor kappaB (NF-kappaB) activation, which is essential for IL-15 gene expression. IL-15 synthesis was detected in rat i-EC on day 1 after an oral inoculation of L. monocytogenes in vivo. The numbers of T-cell receptor (TCR) gamma delta+ T cells, NKR.P1(+) cells, and CD3(+) CD8(+) alpha alpha cells in i-IEL were significantly increased on day 1 after oral infection. The i-IEL from infected rats produced larger amounts of IFN-gamma upon stimulation with immobilized anti-TCR gamma delta or anti-NKR.P1 monoclonal antibodies. These results suggest that IL-15 produced by i-EC may stimulate significant fractions of i-IEL to produce IFN-gamma at an early phase of oral infection with L. monocytogenes.
Hirose
K
K
Laboratory of Host Defense and Germfree Life, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Nagoya, Japan.
Suzuki
H
H
Nishimura
H
H
Mitani
A
A
Washizu
J
J
Matsuguchi
T
T
Yoshikai
Y
Y
D000818:Animals; D015703:Antigens, CD / Q000302:isolation & purification; D000954:Antigens, Surface / Q000302:isolation & purification; D007371:Interferon-gamma / Q000096:biosynthesis; D019409:Interleukin-15 / Q000096:biosynthesis*; D007410:Intestinal Diseases / Q000276:immunology*; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology*; D037181:Lectins, C-Type; D008088:Listeriosis / Q000276:immunology*; D008099:Liver / Q000382:microbiology; D008213:Lymphocyte Activation; D008297:Male; D009059:Mouth Diseases / Q000276:immunology; D016328:NF-kappa B / Q000378:metabolism; D055651:NK Cell Lectin-Like Receptor Subfamily B; D051381:Rats; D011916:Rats, Inbred F344; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000302:isolation & purification; D013154:Spleen / Q000382:microbiology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D015854:Up-Regulation
D015703:Antigens, CD; D000954:Antigens, Surface; D019409:Interleukin-15; D037181:Lectins, C-Type; D016328:NF-kappa B; D055651:NK Cell Lectin-Like Receptor Subfamily B; D016692:Receptors, Antigen, T-Cell, gamma-delta; D007371:Interferon-gamma