One-Time Administration of Recombinant Human Erythropoietin Decreases B Cell in Human Peripheral Blood
Authors: Nagashima Tomomi , Yokohama Akihiko , Nagai Kie , Ino Rumi , Takahashi Noriyuki , Kasamatsu Tetsuhiro , Sekigami Tomomi , Iriuchishima Hirono , Takizawa Makiko , Handa Hiroshi , Saitoh Takayuki , Murakami Hirokazu 
Published: October 2019

Abstract
Introduction:Erythropoietin (EPO) is hematopoietic factors participating in red blood cell production by accelerating cell proliferation and inhibition of apoptosis of erythroblast. It is reported that EPO has pleiotropic effects including anti-apoptotic action for some cells, antioxidant action, vascularization action, and promoting cell division in addition to stimulation of erythropoiesis as well, whereas there are conflicting results of small cohorts as to its effect on blood immune cells. We analyzed peripheral white blood cell subsets in patients who received one bolus administration of recombinant human erythropoietin (rHuEPO) to examine the effect of EPO on human immune system.
Materials and Methods:One hundred twenty eight autologous blood donors (male/female 64/64) in Gunma University Hospital were enrolled in this study after written informed consent. All the patients had no infections or inflammation. Fifty six patients were administered rHuEPO (Epoetin alpha or Epoetin beta, 24,000 IU) once after blood donation because of low hemoglobin concentration (EPO group) and 72 were not administered (non-EPO group). Peripheral blood samples were obtained at the time of the first phlebotomy and after 7 days from the same patient.
We measured the number of WBC, lymphocytes, myeloid dendritic cells (mDC), plasmacytoid dendritic cells (pDC), CD4+ T cells, CD8+ T cells, Natural killer (NK) cells, B cells, monocytes, and neutrophils of peripheral blood before and after rHuEPO administration by flow cytometry. Also we compared EPO group with non-EPO group. Paired and unpaired Student's t-test were used to compare absolute counts and percentages of each cell, P values < 0.05 were considered significant. This study was approved by the research ethics committee of our hospital.
Results:In EPO group, absolute number and percentage of lymphocyte in WBC decreased significantly after rHuEPO administration from 1754.9 ± 535.4/µl to 1627.2 ± 467.7/µl, (p<0.01) and from 30.9 ± 8.00% to 28.2 ± 6.77% (p<0.01), respectively. The numbers of whole WBC, mDC, pDC, monocyte and neutrophil did not show significant changes. In regards to lymphocyte subset, absolute number of CD8+ T cell significantly decreased from 358.9 ± 257.0/µl to 311.5 ± 210.9/µl (p=0.04) and that of NK cell from 290.6 ± 157.6/µl to 257.4 ± 141.8/µl (p<0.01), but their percentages did not change. B cells significantly decreased in absolute number from 258.3 ± 154.2 /µl to 221.6 ± 129.2 /µl (p<0.01) and also in percentages from 14.8 ± 6.92% to 13.6 ± 6.07% (p<0.01). Regarding B cell subsets, absolute number of Naïve B cells significantly decreased from 171.3 ± 93.5 /µl to 153.0 ± 84.2 /µl (p<0.01); moreover other B cell subsets, such as transitional B cells, memory B cells and marginal zone B cells, also showed a trend of decrease, so that the percentage of Naïve B cell did not change in total B cells. These suggested that whole B cell decreased, not a specific subset of B cell. In non-EPO group, there was no significant change in any type of immune cells. When compared the rate of change between before and after rHuEPO treatment, B cell number significant decreased in EPO group compared to non-EPO group (0.87 vs 0.98, p<0.01). Multiple regression analysis revealed rHuEPO administration significantly influenced B cell number (p=0.015); however age, sex, disease status and the type of rHuEPO preparations (epoetin alfa or beta) did not influence.
Conclusion:These findings suggested that just one administration of rHuEPO influenced human immune system, especially via reduction of B cell in peripheral blood.

Disclosures
No relevant conflicts of interest to declare.