The prevalence of the major rhesus antigens in donor blood at the National Blood Transfusion Centre- Nairobi, Kenya
Kimani, S N
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Background In transfusion medicine, the Rhesus blood group system is the most important system after the ABO blood group. It is relevant in many clinical specialities such as obstetrics and neonatology as well as general studies such as population and forensics. It consists of forty nine antigens but only the Rh D antigen is routinely typed in donor blood. The knowledge of the proportions of these Rhesus antigens is helpful in determining the Rhesus status and raises interest whenever there are transfusion related events. This study was therefore undertaken to document the proportion of the major Rhesus antigens in donor blood units sampled. Objectives To determine the prevalence ofthe major Rhesus antigens. Design This was a cross sectional, descriptive study. Setting The National Blood Transfusion Centre, (Nairobi) Kenya and the Kenyatta National Hospital haematology laboratory. The study was conducted between July and September 2010. Methods All the blood samples obtained from eligible consenting donors were tested using standard operating procedures to determine the presence of the Rhesus antigens D, C, c, E and e. Two different Rh D antisera (Biotec Laboratories Ltd and Fortress Diagnostics) were used to test the Rh D antigen. Samples that tested negative with these antisera, were further tested using antihuman globulin and albumin to detect possible Rh D variants. Evaluable Parameters The following parameters were determined and documented; the proportion of donor blood with the antigens D, C, c, E and e, Rh D variant samples as well as the proportion of donor blood with various phenotypes of CcDEe, CcDee, ccDEe, ccDee, ccee, Ccee and CCDee. Results Three hundred and sixty (360) donor blood samples were evaluated for Rhesus antigens and the results were as follows D- 345 (96%), C- 65 (18%), c-356 (99%), E- 68 (19%) and e- 360 (100%). In addition, Rh D variants were detected in 4 (1%) of samples. Other findings showed that the most common phenotype was ccDee- 224 (62%) while the least common was Ccee -2 (1%). Conclusions More than 95% of the donor samples tested were positive for the Rhesus antigens D, c and e while less than 20% of the samples were positive for the Rhesus antigens C and E. Only 1% of donor samples had Rh D variants. Majority of donor samples tested had the phenotype ccDee. Recommendations This study recommended that typing of blood donors be done using Rhesus D monoclonal blend antisera in order to detect possible Rh D variants. In addition, studies should be done to detect the prevalence of alloantibodies in multiply transfused patients. This will determine if there is need to establish phenotypic matching of donor and transfusion dependent recipient.