Solving the dilemma of prevention of red cell alloimmunization

Distribution of Kell phenotype among pregnant women in Sokoto, North Western Nigeria

Introduction

Kell antigen is highly immunogenic and is the common cause of antibody production in mismatched blood transfusions, haemolytic transfusion reaction (HTR) and maternal alloimmunization, which causes severe anaemia in neonates. The aim of this study is to determine the prevalence and ethnic variation of the Kell phenotype among pregnant women in Sokoto, Nigeria.

Methods

Kell antigen status of 150 pregnant women aged 18-45 years and mean age 27.19 ±4.69 years attending antenatal clinic in UDUTH Sokoto Nigeria was determined using the conventional tube method and anti-Kell reagents (Lorne Laboratories, UK).

Results

Among the 150 subjects studied, 3 (2.0%) of subjects were positive and 147 (98.0) were negative for K antigen. Of the 150 pregnant subjects; 32 (21.3%) were primigravidae while 118 (78.7%) were multigravidae. Kell phenotype was more prevalent among primigravidae (3.1%) compared to multigravidae (1.7%) women. The distribution of Kell phenotype among the pregnant subjects was compared based on ethnicity. The prevalence of Kell antigen was significantly higher among the Hausa ethnic group (3.2%) compared to other ethnic groups which indicated zero prevalence (p = 0.001). Kell negative phenotype was ≥ 96.8% among all the ethnic groups.

Conclusion

Our observed prevalence of Kell phenotype is consistent with previous studies among Blacks and Asians but significantly lower than values observed in previous studies among Caucasians. We recommend that all pregnant women should be screened for the presence clinically significant red cell antigens including Kell antigen on their first antenatal visit. Kell negative red cell should be routinely provided for all pregnant women and women with child bearing potential to reduce the risk of Kell-associated HDFN. There is need to introduce routine screening of pregnant women for clinically significant red cell antibodies to facilitate the effective management of HDFN as well as prevent HTR. There is also need for sustained health education of pregnant women in the area to encourage early booking for antenatal care.

Blood Transfusion in the 21st Century

Blood transfusion is a common procedure in the hospital setting, and the safety of the blood supply has been vastly improved over the past few decades largely due to improvements in screening for viral transmissible diseases, especially human immunodeficiency virus (HIV) and viral hepatitis. However, more recent efforts to improve blood safety have focused on non-transmissible disease risks such as transfusion-related acute lung injury (TRALI), non-viral transmissible diseases such as bacterial contamination of blood products (especially platelet components which are stored at room temperature) and Chagas disease (a parasitic disease caused by Trypanosoma cruzi), and prion transmissible agents (e.g., variant Creutzfeldt-Jakob disease, also known as the agent of mad cow disease) as well as more recently-recognized transmissible viral disease risks such as West Nile virus. Appropriate blood utilization has also come under more intense scrutiny in recent times due to healthcare costs and the recognition that many blood transfusions are given under circumstances in which the benefit to the patients is unclear and may be potentially harmful due to the above risks as well as the emerging concept that blood transfusions may cause long-term damage to the immune system resulting in worse patient morbidity and mortality outcomes. Toward that end, accreditation agencies such as the Joint Commission and the American Association of Blood Banks (AABB) are advocating for healthcare organizations to implement appropriate patient blood management strategies. This review will examine these issues along with newer blood safety technological innovations and further highlight contributing studies from our institutions.

Frequencies and specificities of "enzyme-only" detected erythrocyte alloantibodies in patients hospitalized in austria: is an enzyme test required for routine red blood cell antibody screening?

The aim of this study was to determine the frequencies and specificities of "enzyme-only" detected red blood cell (RBC) alloantibodies in the routine antibody screening and antibody identification in patients hospitalized in Austria. Routine blood samples of 2420 patients were investigated. The antibody screening was performed with a 3-cell panel in the low-ionic strength saline- (LISS-) indirect antiglobulin test (IAT) and with an enzyme-pretreated (papain) 3-cell panel fully automated on the ORTHO AutoVue Innova System. The antibody identification was carried out manually with an 11-cell panel in the LISS-IAT and with an enzyme-pretreated (papain) 11-cell panel. In total 4.05% (n = 98) of all patients (n = 2420) had a positive RBC antibody screening result. Of them 25.51% (25/98) showed "enzyme-only" detected specific or nonspecific RBC alloantibodies. Rhesus and Lewis system antibodies were found the only specificities of "enzyme-only" RBC alloantibodies: all in all 4.8% (4/98) were detected with anti-E, 3.06% (3/98) with anti-Le(a), 3.06% (3/98) with anti-D after anti-D prophylaxis and 1.02% (1/98) with anti-e. In total, 14.29% (14/98) showed a nonspecific RBC alloantibody result with the enzyme test. The results of the present study demonstrate that a high number of unwanted positive reactions with the enzyme technique overshadows the detection of "enzyme-only" RBC alloantibodies. (

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K-37-13).