Journal of Behavioral Medicine, Vol. 13, No. 1, 1990 Motivational Syndromes Associated with Natural Killer Cell Activity John B. Jemmott III, 1.2 Caroline HeHman, 3 David C. McCleHand, 4 Steven E. Locke, s Linda Krans, 6 R. Michael Williams, 7 and C. Robert Valeri s Accepted for publication: June 16, 1989 This article reports three studies that taken together support two hypotheses: (a) that the stressed power motivation syndrome is associated with relatively low natural killer cell activity (NKCA) and (b) that the unstressed affiliation motivation syndrome is associated with higher NKCA. In Study 1, college students who were relatively high in stressed power motivation had signifi- cantly lower NKCA than did their peers. In addition, students high in un- stressed affiliation motivation had significantly greater NKCA than did those showing less evidence of this syndrome. Study 2 replicated these findings on a sample of middle-class men. In Study 3, which tested the hypotheses among adult patients from a Health Maintenance Organization, results were in the This work was supported in part by Grant CA-29155 from the National Cancer Institute, Grant MH-1589 from the National Institute of Mental Health, Grant RR-01032 from the National Institutes of Health General Clinical Research Centers Program of the Division of Research Resources, Biomedical Research Support Grant RR-5487 (University Hospital), and a grant from the John D. and Catherine T. MacArthur Foundation. Additional support was provided under the Office of Naval Research Contract N-00014-79-C-1068 with funds of the Naval Medical Research and Developmental Command. The opinions or assertions contained herein are those of the authors and are not to be construed as official or reflecting the views of the Navy Depart- ment or Naval Service at large. ~Department of Psychology, Green Hall, Princeton University, Princeton, New Jersey 05844-1010. 2To whom correspondence should be addressed. 3Department of Psychology, Harvard University, Cambridge, Massachusetts. 4Center for Applied Social Science, Boston University, Boston, Massachusetts. 5Departments of Psychiatry, Harvard Medical School, Cambridge, Massachusetts. *Departments of Psychiatry and Neurology, Boston University School of Medicine, Boston, Massachusetts. ~Department of Medicine, Northwestern University, Evanston, Illinois. *Naval Blood Research Laboratory, Boston, Massachusetts. 53 0160-7715/90/0200-0053506.00/0 9 1990 Plenum Publishing Corporation