NATURAL KILLER CELLS IN HAMSTERS AND THEIR EARLY AUGMENTATION AND LATE SUPPRESSION DURING TUMOR GROWTH

Publisher Summary This chapter examines the natural killer (NK) cells in hamsters and their early augmentation and late suppression during tumor growth. In the study described in the chapter, adult randombred SPF hamsters in a closed isolation colony were given a transplant of 10 7 SA7 cultured tumor cells subcutaneously (SC), and their spleen cell-mediated cytolytic activity was measured at various days post-transplant, along with normal age-matched controls. In addition to the SA7 target, against which specific T-cell immunity may also have been induced, cell-mediated cytotoxicity was also tested against an unrelated (human) target, K562, to assess NK-cell activity more directly, rather than a combination of NK and immune T-cell cytotoxic activity. It was observed that five and seven days post-transplant of SA7 cells, when there was little or no visible tumor, spleen NK activity was greatly augmented. But on day eleven post-transplant, when the tumor was medium in size, activity was 35–39% of control level. At 21 and 28 days when the SC tumor was large, cytolytic activity was even more severely depressed.