Complement Deposition and IgG Binding on Stored Red Blood Cells Are Independent of Storage Time

Evaluation of IgG and Complement Component C4 Levels in Low-Income Countries, Yemen Republic in Light of Their Proposed Role in the Hemolysis of Stored CPDA-1 Whole Blood

Objective

Hemolysis is the most severe change that occurs in stored blood and can cause severe consequences in patients after transfusion. This study examines the potential role of IgG and complement, exampled by C4, in the hemolysis of stored CPDA-1 blood under poor storage conditions in low-income countries.

Methods

The study was performed on 30 whole blood units (250 mL) drawn from convenience healthy volunteer donors with CPDA-1 anticoagulant and stored at 2-6 °C for 35 days. Each well-mixed blood bag was sampled at 0, 7, 21 and 35 days and examined for CBC, plasma hemoglobin, hemolysis percent and determination of IgG and C4.

Results

The plasma hemoglobin level and hemolysis percent increased continuously to reach 1.56 g/dl and 7.05% at the end of storage time. Hemolysis increased alongside the mean IgG concentration that was increased significantly from day 0 of storage (7.68±1.75 g/L) and peaked on day 7 (11.55±1.57 g/L), then declined to reach 8.33±2.09 g/L on day 35. Also, the mean concentration of C4 increased from day 0 of storage (0.15±0.06 g/L) to a peaked on day 21 (0.18±0.04) then declined on day 35 (0.17±0.06 g/L). The coordinated action of IgG and C4 is reflected by the positive correlation of their delta changes (r=0.616, p<0.0001).

Conclusion

Elevated hemolysis percent in whole CPDA-1 stored blood in Yemen was accompanied by initial increase of IgG and C4 followed by final decline, which indicate their activation and consumption during hemolysis. Further studies for other hemolysis markers and analyses will give a full idea about that.

Changes in Complement Levels and Activity of Red Blood Cells, Fresh Frozen Plasma, and Platelet Concentrates During Storage

Complement cascade plays an important role in the field of transfusion medicine. The study aimed to detect the complement levels of different blood components and different blood types to explore the risk of transfusion of stored blood. The samples including red blood cells (n = 110), fresh frozen plasma (n = 120), and platelet concentrates (n = 104) from healthy blood donors in our center were collected. Complement components (C3, C4, C3b, C3d, and CH50) were assayed to evaluate the activation of complement. The complement levels of various blood components at different storage times were observed. The differences in complement levels of four blood types in various blood components were compared. The complement levels of red blood cells in storage were low, with no significant changes (P > 0.05). C3b and C3d levels in platelets began to significantly increase after storage for 3 days (P < 0.05). The fresh frozen plasma during storage had higher complement levels, and the concentrations of C3 and C4 decreased and C3b and C3d increased at month 4 (P < 0.05). The differences in complement levels of four blood types in various blood components did not significantly change (P > 0.05), but the C3b and C3d levels of AB fresh frozen plasma remained stable during storage, which different from other blood types. The transfusion of red blood cells was relatively safe in terms of complement activation. The activation of complement proteins occurred during the storage of platelet and plasma, except group AB plasma.