NK activity in carrageenan-treated mice.

NK activity was determined by measuring 51chromium released from Yac-1 target cells incubated with spleen cells from normal or carrageenan (Car)-treated mice. Intraperitoneal administration of a single dose of i-Car (3 mg) provoked splenomegaly in mice. This splenomegaly accompanied during the first days (2-3), a marked increase of NK activity, then a decrease of this activity at day 8-9. It was returned to normal level at day 30. The modulation of NK activity in Car-treated mice is not due to the variation of the number of NK cells, since the frequency of target-binding cells (TBC) was not modified. The increase in NK activity during the first days may be due to the presence of interferon induced by carrageenan. Concomitant injection of an anti-mouse interferon globulin with carrageenan abolished the boosting of NK activity. NK activity of spleen cells from Car-treated mice at day 8 could not be stimulated by interferon in vitro as it could with the normal spleen cells. No decrease of NK activity was observed in Car-treated mice at day 8, when indomethacin was administered. Hence the decrease of this activity in Car-8 mice might be partially due to the alteration of NK effector cells induced by prostaglandins.