Anomaly of the des-Arg9-bradykinin metabolism associated with severe hypotensive reactions during blood transfusions:: a preliminary study

BACKGROUND: Severe hypotensive reactions have been described after the transfusion of platelets or red cells through negatively-charged bedside white cell-reduction filters. The possibility of a role for bradykinin (BK) in the genesis of these reactions has been raised. STUDY DESIGN AND METHODS: To understand if an anomaly of BK metabolism is associated with these reactions, the metabolism of BK and des-Arg(9)-BK was studied in the sera of four patients who presented with a severe hypotensive transfusion reaction; Tests were performed in the absence and the presence of complete in vitro inhibition of angiotensin-converting enzyme (ACE) activity by enalaprilat. RESULTS: In the presence of ACE inhibition (enalaprilat), the half-life (t1/2) of BK measured in the sera of patients who presented with a severe hypotensive transfusion reaction (361 +/- 90 sec) was not significantly different from that measured in the sera of normal controls (249 +/- 16 sec). In the presence of ACE inhibition (enalaprilat), the t1/2 of des-Arg(9)-BK was significantly greater in patients who presented with a severe hypotensive transfusion reaction (1549 +/- 319 sec) than in normal controls (661 +/- 38 sec) (p<0.001). CONCLUSION: A metabolic anomaly mainly affecting the degradation of des-Arg(9)-BK could be responsible for its accumulation in vivo. Des-Arg(9)-BK could be responsible, at least in part, far severe hypotensive transfusion reactions.