Discriminating complement-mediated acute transfusion reaction for type O+ red blood cells transfused into a B+...

A patient with B+ sickle cell disease received 3 units of red blood cells (RBCs) from two O+ donors and developed fever and hypotension after the first unit, consistent with an acute transfusion reaction (ATR). Anti-B titers in plasma from each O+ donor were markedly elevated and nondiscriminatory. In order to evaluate the potential for the transfused units to produce complement-mediated hemolysis of B+ RBCs, hemolytic complement testing was performed.

Plasma from each donor was diluted in veronal buffer and incubated with B+ RBCs, and free hemoglobin was measured by spectrophotometer in the complement hemolysis using human erythrocytes (CHUHE) assay. Peptide inhibitor of complement C1 (PIC1) was used to confirm antibody-initiated complement pathway activation.

A 96-fold difference (p = 0.014) in hemolysis was measured between plasma samples from the two O+ donors using the CHUHE assay. The extremely high degree of hemolysis produced by the one plasma was inhibited by PIC1 in a dose-dependent manner.

These results indicate that hemolytic complement testing with the CHUHE assay can be used to assess the risk of antibody-initiated, complement-mediated hemolysis from a transfusion beyond what can be achieved with antibody titers alone.