BIOL PSYCHIATRY IS3 1989;26:753-756 Natural Killer Cell Activity in Depressive Illness: Preliminary Report Ziad Kronfol, Madhavan Nair, Joann Goodson, Kavita Goel, Roger Haskett, and Stanley Schwartz Introduction The central nervous system and the immune zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJI sys- tem are closely interrelated. Stress and psychi- atric illness have previously been associated with immune dysregulation (Calabrese et al. 1987). We reported earlier that patients with major depression manifested a reduction in mitogen- induced lymphocyte proliferation, a correlate of cellular immune function (Kronfol et al. 1983). These findings were later confirmed by other investigators (Schleifer et al. 1984). We now report our preliminary results on Natural-Killer (NK) cell activity, a more specific parameter of immune function directed against tumor- or vi- rus-infected cells, in 12 drug-free patients di- agnosed with major depressive disorder and 12 age- and sex-matched normal controls. Subjects and Methods S&ejects There were 12 depressed patients, 5 men. 7 women (mean -+ SD age 36.8 2 9.3). All pa- tients were evaluated at the Department of Psy- From the Departments of Psychiatry (Z.K., M.N., J.G.. K.G., R.H.), Pcdiatncs (M.N., S S.), and Epidemiology (M.N., S.S.), Uni- venity of Michigan Medical Center, Ann Arbor, Ml. Supported in part by NIMH Grant MH-42988 and NIAAA Grant AA-07378 i\ddreu reprint requests to Ziad Kronfol, M.D., Department of Phychlatry. Umvers~ty of Michigan Medical Center. UH-9C. Box 0120. 1500 E. Medical Center Drive, Ann Arbor. MI 4X109- OIX. Kt.cc~\ed December 12. 198X; revised February 9. 1989 chiatry of the University of Michigan Medical Center. Diagnosis was made independently by at least two psychiatrists in an unstructured in- terview using DSM-III criteria as well as Re- search Diagnostic Criteria (RDC) (Spitzer et al. 1977). The RDC diagnosis was confirmed by a structured interview conducted by a trained re- search nurse using the Schedule for Affective Disorders and Schizophrenia (SADS) (Spitzer and Endicott 1975). At the time of the study? 10 patients were hospitalized and 2 were am- bulatory. They all met DSM-III and RDC cri- teria for major depressive disorder and had a score of 2 1.5 on the 17-item Hamilton Depres- sion Rating Scale, HDRS (Hamilton 1960). All patients were also free of drugs known to in- terfere with immune regulation, and free of psy- choactive drugs for at least 2 weeks prior to immune evaluation. In fact, only 3 patients were receiving psychotropic medications (tricyclic antidepressants and/or neuroleptics) 2 weeks prior to the immunological assessment. The mean 2 SD score on the HDRS was 19.5 + 4.8. The mean t SD score on the Carroll Depression Rating Scale (CDRS), a self-rating scale for depression (Carroll et al. 1981) was 29.0 -+ 9.1. The normal control group consisted of 12 healthy volunteers, 5 men, 7 women (mean i SD age 36.5 ? 9.1), who were age and sex matched with the depressed patients. They were recruited in response to ads on the campus of the University of Michigan. Each control sub- ject was interviewed with the SADS-Life Ver- (l(X)h 1723 X%%)J 50