Circadian variations in human peripheral blood on days with and without bone marrow sampling and relation to bone marrow cell proliferation

Fifteen bone marrow (BM) and venous blood circadian profiles were obtained from 13 diurnally-active, healthy men sampled every 4-5 h for 24 h. Periphe ral blood (PB) was also sampled in subsets of 5 men either for 24 h immedia tely preceding the BM procedure or 5-6 months afterwards. Cortisol and whit e and red cell parameters were determined in PB. BM cell cycle distribution was investigated in parallel by flow cytometry for S-phase DNA of total mo nonuclear cells and subpopulations of erythroid and myeloid precursor cells . On a group basis, significant circadian rhythms were found in PB variable s commonly referred to as "marker" rhythms (cortisol, total white tells [WB C], neutrophils [N], lymphocytes [LI), with acrophases less than 2 h apart between the control day prior to and during BM sampling. Thus, major, but r elatively short-lasting physiological stress, like BM aspirations or blood sampling itself although repeated several limes over 24 h, seemed to have m inor influence on these rhythms on days of the BM procedure. When comparing the times of highest or lowest values in PB with times of highest or lowes t values in BM, several temporal relationships were found. Among other asso ciations, timing of lowest values in WBC, N and L or highest values in cort isol was significantly predictive of highest values in myeloid cells occurr ing in the following 12 h, whereas highest values in erythroid cells occurr ed significantly more often in the 12 h interval beginning 4 h after the ti me of lowest values in WBC, L and N. The stability in the circadian rhythms of the PB variables suggests that information obtained on one day can be u sed to guide procedures on the next, such as BM myelotoxic chronotherapy or BM harvesting.