lack of suppressor cell activity for natural killer cells in infant, aged and a low responder strain of mice.

Publisher Summary This chapter discusses the inhibition of natural killer (NK) activity obtained by adding spleen cells of low responding mice that was compared with the inhibition obtained by adding a variety of filler cells. It has been proposed that the low response observed in adult AKR mice and in infant and aged mice of other strains is because of presence of suppressor cells specific for NK cells. Other experiments reporting NK cell suppressors in infant spleens relied on the observed decrease in lytic activity of a normal effector suspension after the addition of infant spleen cells, with no control for possible nonspecific decrease in lysis caused by other factors such as cell crowding. Because a subpopulation of normal thymocytes is susceptible to NK lysis and may competitively inhibit NK lysis of YAC-1 cells, spleen cells were also used as filler cells after culturing to deplete NK activity.