Rh and Kell blood group antigen prevalence in a multi-ethnic cohort in Nigeria: implications for local transfusion service.

CONCLUSIONS: Antigens belonging to the Rh and Kell blood group systems are of major clinical significance because of their immunogenicity and the potential of their consequent antibodies to cause in vivo destruction of exogenous red blood cells (RBCs). Despite the wide-spread use of transfusion, there are sparse data on the prevalence of Rh and Kell system antigens and their ethnic variability in Nigeria. The objective of this study was to determine the prevalence of the five major Rh (D, C, c, E, e) and Kell (K) system antigens in Nigeria with the goal of understanding alloimmunization risk in transfusion recipients and improving transfusion safety through the availability of resources, such as antisera for extended RBC typing and antigen panels for alloantibody detection. A multi-ethnic cohort of 302 healthy Nigerian individuals was created to study RBC antigen prevalence. The antigen status of these individuals for Rh and K antigens was determined using commercially prepared antisera and conventional tube agglutination methods. The prevalence of the Rh antigens in the study cohort was found to be: D (92.7%), C (20.5%), c (97.7%), E (19.5%), and e (97.4%). Dce was the most common Rh phenotype (53.3%). The prevalence of K was 0 percent. For all antigens, there was no association between ethnicity and antigen prevalence. This study is the first to document the prevalence of the major Rh and K antigens in the Nigerian population, using a multi-ethnic cohort. Serologic testing demonstrates a zero prevalence of K antigen, which has never been described. C and E pose the higher risks of alloimmunization, hence showing a need for extended RBC typing and matching in at-risk blood recipients. This study demonstrates that phenotyping for major Rh and K antigens within the Nigerian population can potentially improve transfusion safety and prevent alloimmunization.

Lupus anticoagulant in human immunodeficiency virus -infected patients on highly active antiretroviral therapy.

BACKGROUND: Lupus anticoagulant (LA) is a heterogeneous group of antibodies that causes a variety of clinical and laboratory effects; has been described in infections such as human immunodeficiency virus. LA has not been previously described in Nigerians with human immunodeficiency virus infection on highly active antiretroviral therapy (HAART). AIM: To determine the frequency of LA in patients infected with the human immunodeficiency virus on HAART. METHODS: Cross sectional study of patients with human immunodeficiency virus infection undergoing HAART at a tertiary hospital in Nigeria. Screening for LA was done using the activated partial thromboplastin time (aPTT) and kaolin clotting time (KCT). Mixing experiments were conducted on samples with prolonged clotting time. KCT ratio was calculated. A positive result was taken as KCT ratio greater than or equal to 1.2. Fisher's exact test was used to test the association between LA and sex. Association between aPTT and KCT was tested according to Pearson. P-value < 0.05 was considered significant. RESULTS: Fifty-eight patients aged 18- 60 years were studied, comprising of 28 males (mean age 40.50 plus/minus 8.8 years) and 30 females (mean age 35.4 plus/minus 9.02). Frequency of LA among human immunodeficiency infected patients was 5.2%, (frequency in males and females were 3.6 and 6.7 % respectively). This was lower than 46% reported in patients not on HAART. There was no statistically significant difference in LA prevalence between males and females P greater than0.05. A positive correlation was observed between the clotting tests aPTT and KCT (r is equal to 0.9406, p less than 0.0001). CONCLUSION: HAART may prevent development of LA in HIV-infected patients.