Elevation of Serum Pro-Brain Natriuretic Peptide in G-CSF Stimulated Hematopoietic Progenitor Cell Donors
Authors: Celina Montemayor , West Kamille A , Eder Anne , Cantilena Cathy , Klein Harvey G. 
Published: October 2019

Abstract
Introduction:
Healthy donors who are treated with GCSF before peripheral blood hematopoietic progenitor cell (HPC) collection may develop side effects and aberrant laboratory values that have been described with the mobilization regimen. Alternatively, unexpected abnormal laboratory results could reflect occult complications or underlying disease. While many serum chemistry test results are affected by G-CSF, there have been no published reports describing an effect on BNP (pro-brain natriuretic peptide), a serum marker of heart failure. We encountered a donor who developed an elevated BNP after GCSF-stimulated HPC collection, and investigated its possible association with GCSF administration in healthy donors.
Case Report:
A 41-year old woman was evaluated for matched allogeneic peripheral HPC donation. History and physical exam were unremarkable, and standard laboratory values, EKG and chest X-ray revealed no abnormalities. The donor was mobilized with 10mcg/kg GCSF daily for 5 days. Her only complaint was of headache starting on day 4 that was relieved partially with acetaminophen. No other side effects were recorded.
Her pre-apheresis peripheral CD34+ count was 87/mcL. At the start of apheresis HPC collection, the donor reported headache 7/10 in intensity and intolerance to light, unrelieved by acetaminophen but partially relieved with oxycodone. She complained of nausea during collection, but the procedure was otherwise successful and uneventful (15L of whole blood processed). Her headache persisted at the time of discharge, and the donor was counseled and prescribed one additional dose of oxycodone.
Five hours after discharge the donor reported “the worst headache of her life”, nausea and difficulty breathing. She was evaluated at the ER, where she had stable vital signs and normal oxygen saturation. Her physical exam was unremarkable. Head CT was negative for intracranial hemorrhage or mass effect. A panel of laboratory analyses revealed leukocytosis, decreased platelets, and increased alkaline phosphatase and liver enzymes, which are documented findings associated with GCSF stimulation and large-volume apheresis. Given the donor's complaint of dyspnea, serum BNP was measured and found increased to 483pg/mL (normal <124pg/mL). The donor had a normal pulmonary examination and no clinical evidence of cardiac insufficiency; a chest X-ray and an echocardiogram were also within normal limits. Her symptoms resolved with IV hydromorphone and she was discharged in stable condition. A follow-up serum BNP 4 weeks after donation was within normal range (105pg/mL).
Investigation:
A preliminary study evaluated 11 additional HPC donors who were stimulated with 10mcg/kg GSCF for 5 days (Table 1). Nine of twelve (75%) donors were male, and seven were Caucasian. Ten of the total 12 donors demonstrated an increase in BNP levels compared to pre-stimulation results. Follow-up of four total donors 9-17 days after donation demonstrated return of BNP levels to baseline. None of the donors had clinical evidence of heart failure during stimulation, donation, or follow-up. The average increase in BNP was 4.2 fold, and in a total of 3 donors it exceeded the normal range for the laboratory. The presence or degree of BNP elevation did not correlate with age, gender, severity of GCSF side effects, liver panel results, or pre-apheresis peripheral CD34+ count.
Conclusion:
This case and preliminary study indicate that an increase in BNP levels can be observed in approximately 80% of HPC donors stimulated with 5 days of 10mcg/kg GCSF. The increase in BNP in these donors is not associated with ventricular dysfunction or symptoms of cardiac congestion, and it returns to baseline levels in 2-4 weeks. Two possible molecular mechanisms for this BNP increase include 1) activation of gp130 by increased circulating cytokines associated with GCSF; or 2) direct transcriptional activation of the BNP gene by cardiomyocyte GCSF receptor activation of the JAK-STAT pathway.

Disclosures
No relevant conflicts of interest to declare.