Effect of Plasma Donation on White Blood Cell Count and Metamyelocyte Levels
Plasma donation does not increase white blood cell count (WBC) or metamyelocyte levels; in fact, long-term plasma donation may actually alter certain blood cell populations including decreased percentages of suppressor T cells and natural killer cells with increased percentages of B cells.
Understanding Plasma Donation and Its Effects
Plasma donation is a specific type of blood component donation where only the liquid portion of blood (plasma) is collected through a process called apheresis, while cellular components are returned to the donor.
Plasma Collection Process
During plasma donation:
- Donors undergo apheresis, where blood is drawn from one vein, processed through a cell separator, and the cellular components are returned to the donor through another vein 1
- The process typically takes 1.5-2 hours and involves processing 4,000-5,000 mL of the donor's blood 1
- Modern collection techniques use leukoreduction methods that actually remove white blood cells from the collected product 2
- The final plasma product typically contains minimal cellular components and is stored at specific temperatures for later use 1
Effects on Blood Cell Counts
Research on the impact of plasma donation on blood cell counts shows:
- No evidence of WBC or metamyelocyte increase: None of the guidelines or research evidence suggests that plasma donation increases WBC counts or metamyelocyte levels
- Long-term effects: Long-term plasma donors may actually experience changes in certain blood components:
- Lower serum protein, globulin, and IgG levels compared to non-donors 3
- Increased percentages of B cells (CD19) 3
- Decreased percentages of suppressor T cells (CD8+/CD11b+) and natural killer cells 3
- No significant differences in total white cell counts, percentage of lymphocytes, T cells, or helper T cells 3
Platelet Effects (Not WBCs)
While the question focuses on WBCs, it's worth noting that:
- Regular plateletpheresis donors (a different but related procedure) can develop sustained decreases in platelet count, with a mean decrease of 40,000 per μL from baseline in frequent donors 4
- About 9% of regular platelet donors may be temporarily deferred due to low platelet counts 4
Clinical Implications
The absence of WBC or metamyelocyte increases following plasma donation has important implications:
- Donor safety: Current plasma donation protocols are designed to maintain donor safety with minimal impact on the donor's immune system
- Interpretation of lab results: Recent plasma donation should not be considered a cause of elevated WBC or metamyelocyte counts if observed in clinical testing
- Monitoring requirements: Regular plasma donors should have their serum protein levels monitored rather than WBC counts 3
Conclusion
Based on available evidence, plasma donation does not increase WBC or metamyelocyte counts. If a patient presents with elevated WBC or metamyelocyte levels after plasma donation, clinicians should investigate other potential causes rather than attributing these findings to the donation process.