Minor diurnal and activity-induced variations in daytime peripheral blood platelet counts do not have any major impact on platelet yield by platelet apheresis

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Abstract

Physical activity alters systemic levels of several angioregulatory cytokines that affect microvascular endothelial cells and can be assumed to influence vascular permeability. This may alter platelet release to the bone marrow microcirculation and thereby the levels of circulating platelets. We investigated effects of physical activity on angioregulatory chemokines (CXCL8, 9, 10 and 11) and peripheral blood platelet counts before and after intensive physical activity in young adults, and also compared platelet yields obtained by platelet apheresis performed in the morning and in the afternoon in 20 healthy donors. Physical activity increased serum CXCL10 levels and platelet counts but did not alter the other chemokine concentrations. In the apheresis donors, there was only a minor increase in platelet counts during the day, and the platelet yields did not differ significantly between platelet concentrates collected early in the morning and late in the afternoon. In conclusion, minor intra-individual variations in platelet counts do not seem to have major influence on platelet yields by platelet apheresis.

Introduction

Peripheral blood platelet counts show a relatively wide variation between healthy individuals, and additional diurnal variations are observed [1], [2]. Such variations may influence the platelet yields from platelet apheresis because donor’s peripheral blood platelet concentration is one of the factors that predict platelet yields [3], [4], [5], [6].

The functional status of microvascular endothelial cells is assumed to be important in the regulation of platelet release to the bone marrow microcirculation and will thereby influence the level of circulating platelets. Furthermore, the microvascular endothelial cells are affected by a wide range of angioregulatory cytokines [7], and the systemic levels of these cytokines may thereby influence the levels of circulating platelets. Previous studies have demonstrated that physical activity alters serum levels of several angioregulatory cytokines [8]. In the present study we therefore investigated in more detail the effect of physical activity on serum levels of angioregulatory chemokines and the peripheral blood platelet counts. Finally, we examined whether diurnal variations in platelet counts together with physical activity after an ordinary working day had any impact on the platelet yields from platelet apheresis.

Section snippets

Effects of physical activity on angioregulatory cytokines and peripheral blood cell counts

The studies were approved by the local Ethics Committee (University of Bergen, Norway) and written informed consent was obtained from all participants. The effects of intensive physical activity (cycling) on peripheral blood cell counts and serum levels of angioregulatory chemokines were studied in a group of healthy young adults (5 women and 15 men; median age 22 years, range 20–43 years). These individuals performed 40 min of cycling resulting in a heart rate of 150–170 per minute during the

Intensive physical activity in young adults increases angioregulatory CXCL10 serum levels as well as peripheral blood platelet counts

For the group of young adults (n = 20) the intensive physical activity (cycling) increased peripheral blood platelet counts significantly; the median increase corresponding to 5.6% (Fig. 1A, median 259 × 109/L (range 148–349) versus median 269 × 109/L (range 184–389), P = 0.004∗). On the other hand, a minor decrease in peripheral blood lymphocyte counts was detected (median levels 2.2 versus 2.0 × 109/L, P = 0.021∗), whereas the total leukocyte counts (median counts 6.0 versus 5.9 × 109/L) and neutrophil

Discussion

The peripheral blood platelet counts of the donors influence the platelet yields by platelet apheresis [3], [4], [5], [6]. The platelet count varies between individuals and shows additional minor diurnal variation [1], [2]. In the present study we investigated whether physical activity has an additional effect on peripheral blood platelet counts. In addition we investigated whether variations in platelet counts were associated with altered systemic levels of angioregulatory chemokines. Such

Conflict of interest statement

None declared.

Acknowledgments

The work was supported by the Norwegian Cancer Society, the Solveig and Ove Lunde Foundation and the European Commission (LSHB-CT-2004-503467). The technical assistance of Kristin Paulsen is gratefully acknowledged. We are indebted to all the platelet apheresis donors who participated in the study and to Jorunn Vadheim for the recruitment of the donors. We acknowledge Siren Holme for her support and the Blood Bank personnel at the Haukeland University Hospital for their contribution to the

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