Fig. 2.

Absolute counts of natural T regulatory (nT_reg) and suppression of CD4⁺ T cell proliferation through nT_reg. (a) To analyse the number of CD4⁺CD25⁺ regulatory T cells in peripheral blood we quantified the CD4⁺CD25^high cells indicated by the circle. The percentage of forkhead box P3⁺ (FoxP3⁺) cells within the CD4⁺CD25^high population did not differ over the 24-h period or between the sleep and sleep deprivation condition; 91·5% ± 1% of the CD4⁺CD25^high cells were positive for FoxP3 (data not shown). (b) CD4⁺CD25⁺ regulatory T cells were counted in peripheral blood from healthy men during sleep (closed circles) or sleep deprivation (open circles). (c) CD4⁺CD25⁻ T cells and nT_reg were isolated from peripheral blood of healthy young men with sleep (closed circles) and without nocturnal sleep (open circles). CD4⁺CD25⁻ T cells were stimulated polyclonally either in the presence or absence of nT_reg. The inhibition of CD4⁺CD25⁻ T cell proliferation by nT_reg was calculated (for detailed information see Material and methods). (d) Peripheral blood mononuclear cells (PBMC) and PBMC depleted of nT_reg were stimulated polyclonally and the inhibition of CD4⁺ T cell proliferation through the presence of nT_reg was quantified in cells isolated from healthy young men with sleep (closed circles) or sleep deprivation (open circles). Shaded area indicates bedtime. Mean values ± standard error of the mean (n = 7).