This study was undertaken to determine whether NK-cells constitute a n
ecessary mediator for the suppression of tumor growth by indomethacin.
C57Bl mice with a methylcholantrene (MCG 101) tumor were studied. Ind
omethacin treatment was provided by daily subcutaneous injections (1 m
u g /g body weight). NK-cells were depleted by treatment with a monocl
onal antibody to NK1.1. Consecutive indomethacin injections prolonged
survival in tumor bearing animals. Indomethacin was equally effective
in animals with intact NK-cells as in NK-cell-depleted animals Further
, the MCG cells were apparently insensitive to the lyric activity of N
K-cells in vivo. Thus, the clearance of intravenously injected MCG cel
ls from lungs was nor affected by depletion of NK-cells in vivo; in co
na ast, the corresponding clearance of; NK-cell-sensitive YAC-I lympho
ma cells was strikingly reduced by the depletion of NK-cells. Our data
suggest that NK cells are not a necessary mediator for the suppressio
n of tumor growth by indomethacin.