The NK1.1+T cells alive in irradiated mice play an important role in a Th1/Th2 balance.
OBJECTIVE
Ionizing radiation is known to reduce the helper T (Th) 1 like function, resulting in a Th1/Th2 imbalance. We studied whether NK1.1+T cells which were the most resistant against gamma-irradiation impact on the imbalanced immune response after irradiation.


METHODS
C57BL/6 mice received a whole-body gamma-irradiation (WBI) of 4 Gy. The primary T cells were separated by magnetic cell sorter (MACS) using the anti-CD90.2 antibody. The apoptotic cells were detected by propidium iodide (PI) staining. To determine the Th1 and Th2 cell functions, the production of interferon (IFN)-gamma and interleukin (IL)-4 were analysed by a reverse transcriptase-polymerase chain reaction (RT-PCR) and an enzyme linked immunosorbent assay (ELISA). NK1.1+T cells were detected by flow cytometry. For depletion of the NK1.1+T cells in the WBI mice, anti-asialo GM1 antiserum was injected.


RESULTS
The CD90.2 positive cells of the WBI mice produced significantly more Th2 type cytokines and also produced Th1 type cytokines at a not lower level than normal mice, and contained a higher absolute number of NK1.1+T cells. Also, the proportion of the NK1.1+T cells increased in the WBI mice. We found that the NK1.1+T cells were resistant to radiation-induced apoptosis in comparison with the conventional T cells. The depletion of NK1.1+T cells in WBI mice resulted in higher production of IgE and IL-4 and lower secretion of IL-12p70.


CONCLUSIONS
Our findings revealed that NK1.1+T cells that survive at an early stage after irradiation play an important role in the balance of the immune responses at a late stage after irradiation.
Park
Hae-Ran
HR
Radiation Biotechnology Research Team, Advanced Radiation Technology Institute, Jeongeup Campus of Korea Atomic Energy Research Institute (KAERI), Jeongeup, 580-185, South Korea.
Jo
Sung-Kee
SK
Paik
Sang-Gi
SG
D000818:Animals; D000950:Antigens, Ly; D000954:Antigens, Surface / Q000032:analysis*; D017209:Apoptosis / Q000528:radiation effects; D018664:Interleukin-12 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000502:physiology* / Q000528:radiation effects*; D037181:Lectins, C-Type / Q000032:analysis*; D051379:Mice; D008810:Mice, Inbred C57BL; D055651:NK Cell Lectin-Like Receptor Subfamily B; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D018417:Th1 Cells / Q000502:physiology*; D018418:Th2 Cells / Q000502:physiology*; D018800:Thy-1 Antigens / Q000032:analysis; D014916:Whole-Body Irradiation
D000950:Antigens, Ly; D000954:Antigens, Surface; C527211:Klrb1c protein, mouse; D037181:Lectins, C-Type; D055651:NK Cell Lectin-Like Receptor Subfamily B; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018800:Thy-1 Antigens; D018664:Interleukin-12; D015847:Interleukin-4