Storage of RBCs results in an increased susceptibility for complement-mediated degradation

The objective of this study was to elucidate whether complement activation occurs during the storage of RBCs in newly formulated PAGGS-M storage medium.

The reason for red blood cell (RBC) storage lesions is not yet fully understood. The contribution of complement to RBC storage lesion has not been extensively characterised.

We investigated the surface expression of CD35, CD55, CD59 and CD47, as well as deposition of C3d, using flow cytometry over a storage period of up to 42 days on a weekly basis. C3d and the immunoglobulins IgG, IgM and IgA were additionally investigated via the direct antiglobulin test (DAT). The effect of contact with homologous serum for 30 min at 37 °C was also performed for C3d and CD35 and is subsequently termed as a 'transfusion simulation (TS)'.

A weak but significant increase of C3d was observed prior to TS (anova P = 0.0103), whereas a stronger increase from 74.0 ± 12.4 to 101.2 ± 9.7 was observed post-TS (anova; P < 0.0001). These findings were confirmed by the DAT. CD35, CD55 and CD47 demonstrated a decrease in their expression over storage time (anova; P < 0.0001 each). The majority of changes occurred following 14 days. There was neither a decrease of CD59 observed nor an increase of IgG, IgM and IgA.

RBCs are becoming increasingly susceptible to spontaneous complement deposition following TS, which might be associated with the decrease of C35 and CD55 by proteolytic cleavage and vesiculation during storage. As the impact of storage lesions is rather controversial, institutions involved in blood collection and administration of blood products should focus on carrying out research on the prevention of storage lesions.