The effects of in vivo administration of active lipids (AL-721) on natural killer cell activity and mitogen responsiveness in old rats.

The cytotoxic activity of natural killer (NK) cells under both basal and interferon (IFN)-induced conditions, as well as the proliferative response of lymphocytes to ConA in old rats treated in vivo with AL-721 have been analyzed. The low levels of basal NK cell activity present in spleen of old rats were completely recovered to the levels of NK cytotoxicity obtained in young rats in animals treated in vivo with AL-721. Similar results were obtained for in vitro IFN-boosting of NK cells, in so far as the reduced IFN-responsiveness of NK cells from old untreated rats was restored to the levels of IFN-induced young NK activity in animals treated in vivo with AL-721. The evaluation of the proliferative response of lymphocytes to ConA revealed that old rats treated in vivo with AL-721 showed an increased proliferative capacity in comparison to old untreated animals even if the mitogenic response was not recovered up to the levels observed in young rats.