Activation of complement by blood transfusion filters

Area of Science:

• Immunology
• Transfusion Medicine

Background:

• Blood transfusions involve passing blood products through filters.
• The potential for complement activation during filtration is a concern for patient safety.

Purpose of the Study:

• To evaluate complement activation (C3 and C5a) in citrated blood products filtered through standard filters.
• To determine if microaggregate filters induce significant complement activation.

Main Methods:

• Citrated blood products (fresh blood, stored blood, granulocyte concentrates) were filtered.
• Complement activation was measured by C3 conversion (crossed immunoelectrophoresis) and C5a levels (leukocyte aggregation assay).

Main Results:

• Pre-filtration C3 activation was 0-1% for all products.
• Post-filtration, C3 conversion remained unchanged for fresh blood and granulocytes, with a slight increase to 2-3% for stored whole blood.
• C5a levels showed no significant change after filtration.
• Filter materials alone showed higher C3 conversion in serum (2-10%) compared to citrated plasma (<3%).

Conclusions:

• Microaggregate blood filters induce minimal complement activation in citrated blood products.
• The filtration process is unlikely to cause significant adverse effects related to complement activation during transfusion.