AEGiS-CATIE: Resting may cause T cell counts to fall

Resting may cause T cell counts to fall

TreatmentUpdate81 - Vol. 9, No. 7 - pp. 6-7; September 1997
Sean Hosein

Background & Summary

Monitoring levels of CD4+ cells helps doctors keep track of the state of the immune system. As CD4+ cell counts are used when making decisions about therapies it is important that the counts are as accurate as possible. Several factors can affect CD4+ cell counts including the time of day the blood was drawn, stress and exercise. Researchers in England have focused on people at rest and found that in that state, CD4+ cell counts can fall by 38% and CD8+ counts by 32% compared to blood taken from people who had not been resting.

Study Details

Researchers recruited 20 volunteers who were all healthy lab workers (average age was 33 years and the number of males and females was not released) for this study. Blood samples were taken at 8am then 30 and 60 minutes later. At 4 pm more blood samples were obtained . Between 8am and 9am the volunteers were lying semi-reclined on their backs. After 9am they began their normal daily activities.

Results

Before resting, at 8am the cell counts were:

* CD4+: 1060

* CD8+: 790

After 30 minutes rest:

* CD4+: 800

* CD8+: 540

After 60 minutes rest:

* CD4+: 660, a 38% decrease from the 8am measurement

* CD8+: 610, a 32% decrease from 8am

These decreases in the CD4+ and CD8+ cell counts were statistically significant; that is, not likely due to chance alone. By 4 pm, after subjects had resumed their normal work activity, the counts had increased:

* CD4+: 1,010

* CD8+: 750

The researchers do not think that these changes seen earlier in the day were due to daily biorhythms. By the end of the day there was no overall change in T cell levels. Keep in mind that:

* the volunteers used in this study were not HIV-infected so it is not clear what would happen in such people if they were rested before T cell measurements were done.

Nevertheless, a large period of inactivity, 30 to 60 minutes, before having blood drawn for T cell measurements may provide a less than normal result.

REFERENCES:

1. Campbell PJ, Aurelius S, Blowes G and Harvey D. Decrease in CD4+ lymphocyte counts with rest; implications for the monitoring of HIV infection. International Journal of STD & AIDS 1997;8:423-426.

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