Abstract
In 1979, anti-C9 antibody was found in a patient with hereditary C9 deficiency. This patient had received multiple transfusions with several units of blood. The detection of C9 deficient patients and follow-up of those transfused were done in 52, 000 patients treated at Kyushu University Hospital to investigate the frequency of C9 deficiency, and the incidence of anti-C9 precipitating antibodies in transfused patients. Transfusion reactions in recipients having anti-C9 antibody were also monitored. The study identified twelve patients with C9 deficiency (a prevalence of 0.023%). Three out of twelve patients had received transfusions. One of the patients who had received several units of blood within a week, produced low-titer anti-C9 precipitating antibody. This patient was transfused in the presence of anti-C9 precipitating antibody without evidencing transfusion reactions. No precipitating antibody was detected in the remaining two patients who had received several units of blood during the course of a single day.
These observations suggest that one of the factors that may be conducive to the development of anti-C9 antibody is the frequency of multiple transfusions. Furthermore the likelihood of transfused C9 deficient patients developing transfusion reactions is minimal.
