ABSTRACT
This chapter reviews the major findings concerning the characterization, and the role of suppressor cells in regulation of Natural killer (NK)cell activity in normal animals and in those treated with various immunomodulating agents. NK cells have cytotoxic activity in vitro against a variety of tumor cells, against some microorganisms, and against cells which are infected with microbial agents. The levels of NK activity in rodents have a characteristic age-related fluctuation. In addition to agents which augment NK activity, a variety of agents have been shown to inhibit NK function. Low NK cell responsiveness of normal rodents is influenced by various factors, including the age of the animals. The observations on the regulation of NK cell activity by suppressor cells in young and aged animals and its association with higher incidence of tumors deserves further investigation.
