A novel role of IL-15 in early activation of memory CD8+ CTL after reinfection.
A rapid induction of effector functions in memory T cells provides rapid and intensified protection against reinfection. To determine potential roles of IL-15 in early expansion and activation of memory CD8+ T cells in secondary immune response, we examined the cell division and cytotoxicity of memory CD8+ T cells expressing OVA(257-264)/Kb-specific TCR that were transferred into IL-15-transgenic (Tg) mice, IL-15 knockout (KO) mice, or control C57BL/6 mice followed by challenge with recombinant Listeria monocytogenes expressing OVA (rLM-OVA). In vivo CTL activities and expression of granzyme B of the transferred CD8+ T cells were significantly higher in the IL-15 Tg mice but lower in the IL-15 KO mice than those in control mice at the early stage after challenge with rLM-OVA. In contrast, there was no difference in the cell division in IL-15 Tg mice and IL-15 KO mice compared with those in control mice. In vivo administration of rIL-15 conferred robust protection against reinfection via induction of granzyme B in the memory CD8+ T cells. These results suggest that IL-15 plays an important role in early activation of memory CD8+ T cells.
Yajima
Toshiki
T
Division of Host Defense, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan. yajimato@biored.kyushu-u.ac.jp
Nishimura
Hitoshi
H
Sad
Subash
S
Shen
Hao
H
Kuwano
Hiroyuki
H
Yoshikai
Yasunobu
Y
D019264:Adoptive Transfer; D000818:Animals; D007114:Immunization; D007156:Immunologic Memory; D019409:Interleukin-15 / Q000172:deficiency / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000276:immunology / Q000472:pathogenicity; D008088:Listeriosis / Q000276:immunology / Q000517:prevention & control; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011994:Recombinant Proteins / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D019409:Interleukin-15; D011994:Recombinant Proteins