EFFECTOR AND TARGET-CELLS IN THE ASSESSMENT OF NATURAL CYTOTOXIC ACTIVITY OF RHESUS-MONKEYS

In humans, decreased natural killer cell (NK) activity has been associ ated with stressful life events, whereas acute arousal and disturbance frequently has been reported to result in increased NK activity. This bidirectional immune modulation prompted us to investigate the effect s of a social stressor on the lymphocyte cytolytic activity of 31 infa nt rhesus monkeys. The first of three studies evaluated the effects of an 8 hr maternal separation on the infants' cytolytic response agains t the K562 target-cell line. A finding of increased lytic activity ind icated a need for a longer evaluation-after a 24 hr separation-and an additional assessment of two other target-cell lines, Raji and Daudi. The observation of decreased lytic responses to Raji and Daudi, in ass ociation with increased lysis of K562, warranted a third study to deli neate which rhesus effector cells were responsible for lysis of the K5 62 and Raji target cells. By isolating cell subsets, it was possible t o observe that the majority of unprimed cytotoxic activity resided in the CD3- population of cells, but that the CD3+ CD8+ population also m ediated a significant amount of cytotoxicity against both targets. In conclusion, these findings support earlier studies indicating that mat ernal separation results in significant immune alterations in infant m onkeys. However, the complex nature of changes in cytotoxic responses during prolonged stress revealed that different lymphocyte populations engage in parallel and compensatory alterations. (C) 1996 Wiley-Liss, Inc.