The ABO system was discovered in 1990 and remains until today the most important system in transfusional practice. The wrong ABO transfusion can result in death of the patient after a hemolytic reaction followed by immunological and biochemical changes. ABO antibodies are found in the serum of individuals, and are directed against the A and B antigens absent in the red cells. Although transfusions with low quantities of incompatible plasma are generally considered a safe practice, some cases of hemolytic reactions owing to incompatible plasma are described in the literature. Despite the lack of information about anti-A and anti-B hemolysins and the importance of this antibody in transfusional practice, we proposed in this work to investigate the frequencies of these hemolysins in blood donors from de Hemotherapy Center of Unesp Botucatu. Six hundred samples of blood sera from voluntary donors of the "O" blood group were analyzed to test for the presence or absence of anti-A and anti-B hemolysins. A total of 77 (12.8%) of the donors were classified as high-risk donors with the presence of high serum levels of hemolysins and 523 (87.2%) were classified as safe, presenting with low levels of hemolysins. In the group of high-risk donors, 45 (58.4%) reacted with anti-A hemolysin, 11 (14.2%) reacted with anti-B hemolysin and 21 (27.2%) reacted with both of the hemolysins. Donors with a hemolysin level of over 1/100 were considered as high-risk "O" donors. The tests performed in our daily routine is enough to detect high levels thereby avoiding the risk of other blood group patients having transfusional reactions when there is a need of receiving blood transfusions from other blood group donors.
ABO system; anti-A and anti-B hemolysins; high-risk "O" blood donors
