The D phenotype distribution in G2 resembles that in Europeans while the frequencies in G1 account for the Amerindian and African genetic contribution. The genotyping strategy described here is suitable to study D variants in the overall population and could allow a better use of the few available D- units and a rational administration of anti-D immunoprophylaxis. The results also show that weak D Type 1 alleles do not exclusively segregate with a Ce allele, as assumed until present.

The prevalence of D-/RHD+ samples is higher than that observed in Europeans. More than 50% of the RHD alleles found were represented by RHDψ and RHD-CE-D(s) showing the African contribution to the genetic pool of the admixed population analyzed. Interestingly, three new alleles were found, two of them being hybrid structures between previously described RHD variants recombined with RHCE sequences. The knowledge of the RHD allele repertoire in our population allowed the implementation of reliable typing and transfusion strategies for a better management of patients and pregnant women.

Background: Kell null (K₀) individuals can produce anti-Ku, an antibody against many epitopes in the Kell glycoprotein, after transfusion and/or pregnancy. Since sensitized K₀ patients are rare, little is known about anti-Ku clinical relevance and in particular about its association to hemolytic disease of the fetus and newborn. Case Report: This work describes a case of neonatal hyperbilirubinemia due to immune-mediated erythrocyte destruction by an alloantibody directed against the Kell glycoprotein. Serologic and molecular approaches identified an anti-Ku alloantibody in maternal serum. A homozygous IVS3 + 1g>a point mutation (KEL*02N.06 allele) was found to be responsible for the lack of Kell antigen expression in the mother's red blood cell and subsequent alloimmunization after a previous pregnancy. Even though in most cases Kell antibodies are clinically severe and may cause suppression of erythropoiesis, in our case the newborn had a moderate anemia and hyperbilirubinemia that was successfully treated with phototherapy without requiring exchange transfusion. Serological and molecular studies performed in the proband's family members allowed us to provide them with proper counseling regarding alloimmunization after transfusion and/or pregnancy. Conclusions: This case enlarges the understanding of the clinical significance of alloantibodies against Kell blood group antigens.

Background: Mature red blood cells lack protein synthesis and are unable to restore inactivated enzymes, damaged cytoskeleton and membrane proteins. An oxidation breakdown of band 3 is probably part of the mechanism leading to the generation of a senescent cell antigen. This specific signal serves for the clearance of RBCs by inducing the binding of autologous IgG and C3, leading to phagocytosis. In addition, phosphatidilserin molecules appear in the outer membrane and the CD47 expression diminishes. Methods: Erythrocytes of different ages from whole blood were studied by flow cytometry analysing light scatter proprieties, binding of autologous IgG, C3 complement deposits, externalization of phosphatidylserine and CD47 expression. Dot-plot analysis based on forward scatter versus side scatter parameters showed two RBCs populations of different sizes and density. RBCs were further incubated with Alexa 488 IgG, APC-anti-C3, PE-annexin-V and PE-CD47. The comparison of the values obtained for the different variables studied in SeRBC and YRBC populations was carried out by the Student t-test for matched samples or by the Wilcoxon test (after verification of the normality assumption). Results: The percentage of IgG and C3 positive cells was significantly higher in senescent red blood cells population. The fraction of annexin-V positive RBCs was also larger in SeRBCs while the CD47 expression was lower in this population. Conclusions: These results indicate that flow cytometry allow differenciation of erythrocytes populations of different ages, turning this tool into an useful alternative option to study erythrocyte aging process. These findings will contribute to a better understanding of the process and mechanisms involved in erythrocyte senescence process.