CIRCADIAN IMMUNE MEASURES IN HEALTHY-VOLUNTEERS - RELATIONSHIP TO HYPOTHALAMIC-PITUITARY-ADRENAL AXIS HORMONES AND SYMPATHETIC NEUROTRANSMITTERS

Objective: The purpose of this study is to examine the circadian patte rn of specific immunologic measures and to compare observed circadian rhythms of these measures with the well-established circadian rhythms of hypothalamic-pituitary-adrenal axis hormones and sympathetic neurot ransmitters. Methods: Blood samples were collected every 2 hours for a total of 24 hours from nine healthy volunteers. The blood samples wer e assayed for hormones and immune measures, including adrenocorticotro pic hormone (ACTH), cortisol, norepinephrine, and epinephrine. The imm une measures included percentage and absolute number of neutrophils, l ymphocytes, the lymphocyte subsets CD3+ (T cells), CD4+ (T helper/indu cer), CD8+ (T suppressor/cytotoxic), CD56+ (natural killer [NK] cells) and NK cell activity (NKCA). Results: The following immune measures e xhibited a significant circadian rhythm: the percentages of neutrophil s, CD4+ cells, and CD56+ cells; the absolute numbers of total lymphocy tes, CD3+ cells, CD4+ cells, and CD8+ cells; and NKCA. Cross-correlati ons between the circadian rhythms of selected hormones and immune meas ures indicated a strong inverse association between the circadian rhyt hms of cortisol and the different T cell subsets on the one hand, and a strong direct association between the rhythms of cortisol and the pe rcentage of CD56+ and NKCA on the other. Cross-correlations involving the circadian rhythms of norepinephrine and the same immune measures w ere in general much weaker and statistically nonsignificant. Conclusio n: In healthy individuals, both enumerative and functional immune meas ures exhibit circadian rhythms that seem to be associated most closely with the circadian rhythm of cortisol.