Controls and transplant recipients differ in the circadian rhythm of cell counts. Circadian rhythm of (A) leukocytes and their subpopulations, namely (B) neutrophils, (C) monocytes, (D) lymphocytes and their subpopulations (E) NK-cells, (F) B- and (G) T-lymphocytes in peripheral blood of healthy controls (n = 6), long-term (n = 12) and short-term transplanted patients (n = 7) was determined over 24 hours at 8:00 a.m., 12:00 p.m., 8:00 p.m., 12:00 a.m. and the following day at 8:00 a.m. Shown are the differences in cell numbers with respect to the mean that was calculated from all values analyzed over the 24 h-time period (stippled line). The variance of cell populations at each time point with respect to this 24 h-mean is expressed as mean ± standard error of the mean. Statistical analysis was performed using the repeated measures ANOVA with Tukey’s post-test. Statistically significant differences are indicated with respect to the initial 8:00 a.m. sample. * p < 0.05, ** p < 0.01, *** p < 0.001.