The immunoregulatory roles of natural killer T cells in cyclophosphamide-induced tolerance.
BACKGROUND
Recent studies have indicated that natural killer T (NKT) cells are essential for the establishment of transplantation tolerance. In the present study, we have elucidated the role of recipient and donor NKT cells in cyclophosphamide (CP)-induced tolerance.


METHODS
DBA/2 (DBA; H-2) mice were used as donors and BALB/c (BALB; H-2) wild-type (WT) or Valpha14 NKT-knockout (KO, BALB/c background) mice were used as recipients. Recipients were treated with CP-induced tolerance regimen, which consists of donor spleen cells (SC) on day 0 and CP on day 2. In some experiments, NKT KO mice, which received NKT cells from either WT, inferon-gamma KO, or interleukin-4 KO mice, were treated with tolerant regimen. To deplete Ly49 inhibitory receptors on NKT cells in the recipient mice, anti-Ly49 monoclonal antibody cocktails were injected on day -1 when indicated.


RESULTS
Donor skin graft was permanently accepted in recipient BALB WT mice with induction of donor mixed chimerism. On the contrary, donor DBA skin allografts were chronically rejected in NKT KO recipient. Lower levels of mixed chimerism were observed in NKT KO recipients comparing to the WT recipients. The production of interferon-gamma or interleukin-4 from NKT cells did not affect the induction of tolerance. Depletion of Ly49 positive NKT cells abrogated the induction of skin graft tolerance.


CONCLUSIONS
Recipient NKT cells, but not donor NKT cells, were dominantly required for the induction of allograft tolerance. Our results indicated that the single cytokine produced by NKT cells did not mediate the regulatory function in the induction of allograft tolerance.
Iwai
Toshiro
T
Department of Cardiovascular Surgery, Kyushu University, Fukuoka, Japan.
Tomita
Yukihiro
Y
Shimizu
Ichiro
I
Kajiwara
Takashi
T
Onzuka
Tatsushi
T
Okano
Shinji
S
Yasunami
Yohichi
Y
Yoshikai
Yasunobu
Y
Nomoto
Kikuo
K
Tominaga
Ryuji
R
D000818:Animals; D003520:Cyclophosphamide / Q000627:therapeutic use*; D005434:Flow Cytometry; D006085:Graft Survival / Q000276:immunology; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007694:Killer Cells, Natural / Q000276:immunology*; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D023421:Models, Animal; D016038:Skin Transplantation / Q000276:immunology*; D014184:Transplantation, Homologous / Q000276:immunology*
D007166:Immunosuppressive Agents; D003520:Cyclophosphamide