CIRCADIAN-RHYTHMS OF CIRCULATING NK CELLS IN HEALTHY AND HUMAN IMMUNODEFICIENCY VIRUS-INFECTED MEN

Antiviral immunity involves NK cells, which circulate rhythmically eve ry 24 hours. We have investigated circadian and 12-hour rhythms in the peripheral count of circulating NK cells in 15 men infected with huma n immunodeficiency virus (HIV) and 13 healthy controls. We analyzed th ree phenotypes using double-labeling with monoclonal antibodies and fl ow cytometry assessment: CD3- CD16+, CD3-CD57+, and CD2+CD3-. A statis tical validation of time-dependent differences was achieved if signifi cance (p < 0.05) was validated both with analysis of variance and cosi nor. The circadian rhythm had a similar asymmetric waveform for the th ree phenotypes and is homogeneous on an individual basis. The circulat ing NK cell count peaked in the early morning and was low at night. A circadian rhythm and a circahemidian harmonic characterized all phenot ypes in healthy subjects. We considered two groups of HIV-infected men : those who were asymptomatic (eight) and those with acquired immune d eficiency syndrome (AIDS) (seven). Circadian changes in NK cell count were similar in both subgroups and in healthy controls. The circadian pattern was also consistent among individual patients. Asymptomatic HI V-infected men (early-stage disease) exhibited more pronounced 12-hour rhythmicity than did patients with AIDS or controls. The circulation of NK cells does not appear to share the same synchronizer(s) as other circulating T- or B-lymphocyte subsets. Thus, HIV infection gradually abolished circadian rhythmicity in circulating T and B cells, whereas it did not disturb that in NK cells.