Inhibition of lung natural killer cell activity by smoking: the role of alveolar macrophages.
BACKGROUND
It is known that natural killer (NK) cell activity in the lung of smokers (SM) is lower than in non-smokers (NS). However, little is known about the underlying mechanisms.


OBJECTIVE
The purpose of this work was to investigate the mechanisms of the inhibition of NK cell activity by alveolar macrophages (AM) in SM.


METHODS
Lung effector cells and AM were obtained using bronchoalveolar lavage. The NK cell activity was assayed by 51Cr release method after incubation of 4 and 24 h, using K562 as target cell. AM were added at a concentration of 25% to effector cells.


RESULTS
Following 24-hour culture, NK cell activity significantly increased in the NS but not in the SM. Lung NK cell activity was significantly augmented by interleukin-2 in the NS but not in the SM. Addition of AM to the NK cell preparation from SM exerted a significantly greater suppressive effect on autologous blood NK cell activity than in the NS. Indomethacin, catalase or thiourea did not prevent AM-mediated suppression of NK cell activity, in contrast to superoxide dismutase.


CONCLUSIONS
These results suggest that the suppression of NK cell activity by AM in SM may be caused by O2- release rather than by prostaglandins, H2O2 or OH release from AM.
Takeuchi
M
M
Department of Biotechnology, Faculty of Engineering, Kyoto Sangyo University, Kyoto, Japan. mtakex@cc.kyoto-u.ac.jp
Nagai
S
S
Nakajima
A
A
Shinya
M
M
Tsukano
C
C
Asada
H
H
Yoshikawa
K
K
Yoshimura
M
M
Izumi
T
T
D000328:Adult; D001992:Bronchoalveolar Lavage Fluid; D006801:Humans; D007694:Killer Cells, Natural / Q000502:physiology*; D008168:Lung / Q000166:cytology*; D016676:Macrophages, Alveolar / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000503:physiopathology*