ENHANCEMENT OF TUMOR COLONY FORMATION IN LUNGS OF MICE BY TUMOR-NECROSIS-FACTOR

The influence of TNF on tumor colony formation and natural killer (NK) cell activity in C57BI/6 mice depending on the doses and time of cyto kine treatment was investigated. It was shown that INF injected 4 h be fore tumor cell injection in a dose-depended manner enhanced tumor cel l arrest in lungs and sharply stimulated metastasis. This effect of TN F was also observed when it was injected many hours; after tumor cell injection when most of them had been already arrested in lung or elimi nated from the blood stream. Inoculation of TNF i.v. was accompanied b y a rapid (4 h) inhibition of NK cell activity which restored only in 48 h. Possible mechanisms of TNF modulation of NK cell activity are:di scussed.