title: Circadian changes in human natural killer-cell activity.
abstract: The circadian changes in natural killer (NK) activity of peripheral blood mononuclear cells (PDM) were studied in five clinically healthy, diurnally active, nocturnally resting women. Data on spontaneous NK-cell activity were complemented by data on the chronosusceptibility to in vitro inhibition by 1 X 10(-6) M cortisol and by the rhythmometric evaluation of rectal temperature and plasma cortisol as potential circadian markers. In April-July, 1985, blood was drawn at 4-hr intervals for 24 hr starting at 0800 hr. Cells were immediately separated and assayed for NK activity using K 562 cultured cells as a target and a 4-hr 51Cr-release assay. Circadian variations of the spontaneous NK activity were apparent; the maximum of the activity occurred in the morning or in the early afternoon. In individual subjects, peak-to-through differences were 50% or more of the 24-hr mean. Chronosusceptibility to cortisol (20 hr incubation prior to the cytotoxic assay) was ecphasic with respect to the spontaneous NK-cell activity, with a maximum in the evening or night. Data obtained by immunofluorescence using specific anti-NK cell monoclonal antibodies confirm the occurrence of a higher number of phenotypically identifiable NK effectors in the morning vs. other circadian stages. Our data confirm previous findings and extend their scope to immunopharmacology emphasizing the need for time-qualified investigations on immune coordination in vivo.
authors.forename: G
authors.initials: G
authors.lastname: Gatti
authors.forename: D
authors.initials: D
authors.lastname: Del Ponte
authors.forename: R
authors.initials: R
authors.lastname: Cavallo
authors.forename: M L
authors.initials: ML
authors.lastname: Sartori
authors.forename: A
authors.initials: A
authors.lastname: Salvadori
authors.forename: R
authors.initials: R
authors.lastname: Carignola
authors.forename: F
authors.initials: F
authors.lastname: Carandente
authors.forename: A
authors.initials: A
authors.lastname: Angeli
mesh_terms: D000328:Adult; D001831:Body Temperature; D002940:Circadian Rhythm; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000494:pharmacology; D007206:Individuality; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D007958:Leukocyte Count
chemical_list: D006854:Hydrocortisone