Optimal blood grouping and antibody screening for safe transfusion

(Full text is available at http://www.manu.edu.mk/prilozi). Introduction. Blood group antigens as integrated parts of the red cell membrane have many essential functions for the cell as well as for the organism, but they are recognized as unique antigens for the purpose of safe blood transfusion. Especially in the case of those with great clinical importance because of their involvement in haemolytic transfusion reactions and hemolytic disease of the newborn, it is very important that they be correctly, and some of them routinely, typed in blood donors as well as in patients. Aim. Evaluation of Rh and Kell blood group antigen frequencies in blood donors as well as the incidence of alloimmunization in transfused patients in the Macedonian population. The need for routine typing of certain blood group antigens in addition to ABO and RhD was also evaluated. Material and method. We evaluated data from 1600 ABO/Rh and Kell typed blood donors (from January 2003 to May 2008), as well as the data from pretransfusion testing (ABO/RhD blood typing, irregular red blood cell antibody screening and compatibility testing) and antibody identification in the period from January 2005 to November 2008. All tests were performed by the DiaMed micro tube gel system. Results. The frequencies of ABO antigens were as follows: A (39.7%), O (38%), B (14.1%), AB (7.4%). The frequencies of Rh antigens were as follows: D pos. (84.2%), D neg. (15.8%), C (58.3%), c (82.4%), E (21.3%), e (97.1%). We found the following frequencies of Kell phenotypes: K+ k- (0.25%), K+ k+ (6.18%), and K- k+ (93.6%) with the total frequency of K antigen of 6.4%. Antibody screening and/or cross-match were positive in the sera from 150 transfused patients. In 75 (50%) sera the following 81 antibodies were identified: anti-K (26), -E (25), -e (1), -C (4), -c (6), -C(w) (2), -k (1), -Fy (a) (3), -Fy(b) (1), -Jk(a) (3), -Lu(b) (1), -Le(b) (2), -Le(a) (1), -M (4), -P1 (1). The most frequent alloantibody was anti-K with 32%, and anti-E with 30.8% of all identified antibodies. Conclusion. Alloimmunization to red cell antigens is still a current problem in our transfusion practice. It is obvious that the additional testing of blood donors for Rh and Kell antigens should be implemented as a routine to prevent as far as possible the incidence of alloimmunization. It would also be cost-effective, bearing in mind the additional laboratory testing necessary to provide compatible blood for alloimmunized patients. Extended blood typing should be implemented for some categories of polytransfused patients as well. This strategy is another step forward to improve the safety of blood transfusion with optimal blood grouping. Key words: Kell phenotypes frequency, alloimmunization, blood grouping, safe transfusion.