Background/Case Studies: Granulocyte transfusions represent a therapeutic option for neutropenic patients with bacterial or fungal infections that are otherwise unresponsive to conventional therapy. Previous research has correlated larger numbers of transfused granulocytes with improved clinical outcomes. Thus, a suboptimal donor stimulation and collection can have significant and negative impacts on the granulocyte dose, which can result in reduced efficacy and worsened clinical outcomes. Here we investigated possible donor characteristic correlations (age, gender, body weight (BW), body mass index (BMI), baseline hemoglobin (Hgb), and platelet counts) with the Δ WBC (post stimulation WBC count-baseline WBC count) to predict the efficacy of mobilization to better identify the ideal granulocyte donor population.
Study
Design/Methods: Data from 267 leukocytapheresis collections from healthy donors performed at a hospital-based donor center from 2020 to 2022 were retrospectively reviewed (IRB:2022-0974). Donors were stimulated with 480 mcg of G-CSF IFilgrastim) subcutaneously, and 8 mg of dexamethasone orally administered 12 to 14 hours prior to collection. Statistical analysis was performed using GraphPad Prism software. Statistically, variable correlation was assessed using Pearson’s correlation coefficient.
Results/Findings: A total of 198 donors underwent 264 leukocytapheresis procedures. The median donor age was 46 (18-81) years. There was no significant difference in mobilization efficiency by gender. Male donors had a median Δ WBC of (24.0) and female donors had a Δ WBC of (25.6), (p=0.198). A negative correlation was observed between efficacy of mobilization (Δ WBC) and age (r=-0.221, p=0.0003, n=264), (Figure A). Donor’s BMI values ranged from 17.9 to 46.3 (median 28.9). Donor body weight and BMI did not correlate with mobilization efficacy. However, a positive, but weak correlation was found between baseline platelet counts and WBC mobilization (r=0.110., p=0.07, n=263). No correlation was observed with baseline Hgb (r=.06, p=0.320, n=263). Conclusions: Mobilization efficiency was not impacted by donor BW or BMI suggesting that body weight-based G-CSF and dexamethasone stimulation is not essential for improved granulocyte collection. Rather, a fixed single dose of 480 mcg of G-CSF and 8 mg of dexamethasone was sufficient to mobilize patients, thus reducing the procedural costs and the potential risks for medication-related side effects. The negative correlation between age and Δ WBC following granulocyte mobilization guided us in the decision to establish 70 years old as the age limit for granulocyte collection. The weak positive association of mobilization efficiency with baseline platelet count may be confirmed with an increase in sample size. Association between baseline PLT and pre-apheresis CD34+ cell counts in PBSC donors has previously been reported [1].
Reference: 1-Leitman et al. Blood. 2008;112:2092–2100
Importance of research: The findings of this study may provide a better understanding of the factors that contribute to successful granulocyte donor mobilization and subsequently granulocyte collection yield. Our study highlights donor factors important to predict the ideal granulocyte donor population.
