Weak D antigen - Revisited.

D antigen is the most immunogenic antigen in the complex Rh blood group system discovered in the year 1939. There is a lot of polymorphism in its phenotype due to genetic heterogeneity. Certain mutations and /or deletions lead to a weak phenotype defined by decreased density of antigen sites which require the use of anti human globulin for detection. The need for detection of the weak D antigen was to prevent alloimmunization by this blood if transfused to a D negative patient especially to women in child bearing age group. This contention is however, controversial and not proven beyond doubt. Moreover, the use of potent monoclonal D typing antisera detects low density of weak D antigens thus obviating the use of anti human globulin. We have assessed the incidence of Rh negative and weak D blood groups in the Garhwal region of Uttarakhand and reviewed the literature regarding the controversies in the clinical significance of weak D antigen.

Seroprevalence of anti-helicobacter pylori and anticytotoxin-associated gene a antibodies according to abo blood groups and rhesus status among hemodialysis patients

Correlation between Helicobacter pylori infection and blood group typing has been widely evaluated in both patients and healthy population. However, data addressing this correlation in hemodialysis patients are scarce. The aim of this study was to evaluate the prevalence of anti-Helicobacter pylori and anticytotoxin-associated gene A [anti-Cag A] antibodies and their correlations with ABO blood groups and rhesus blood group status in hemodialysis patients. In a cross-sectional study, serum samples of 151 hemodialysis patients were tested for anti-Helicobacter pylori IgG antibody. Anti-Cag A antibody [IgG antibody] was tested in Helicobacter pylori-positive patients. ABO blood groups typing and rhesus status were tested by hemagglutination test. Prevalence of anti-Helicobacter pylori and anti-Cag A antibodies in Helicobacter pylori-positive patients were 65.6% [99 of 151] and 25.3% [25 of 99], respectively. Prevalence of anti-Helicobacter pylori and anti-Cag A antibodies were 69.1% and 36.8% in patients with blood group A, 42.3% and 9.1% in blood group B, 75.0% and zero in blood group AB, 69.4% and 23.3% in blood group O, 59.0% and 30.6% in rhesus-positive status and 89.7% and 11.5% in rhesus-negative status, respectively. There was a significant correlation between the presence of anti-Helicobacter pylori and anti-Cag A antibodies and rhesus status, but no significant relation between ABO blood groups and anti-Cag A antibodies were found. Rhesus status may have an impact on the presence of anti-Helicobacter pylori and anti-Cag A antibodies. More investigations to address this correlation are necessary

Immunologic basis and immunoprophylaxis of RhD induced hemolytic disease of the newborn [HDN]

RhD antigen is the most immunogenic and clinically significant antigen of red blood cells after ABO system. It has historically been associated with hemolytic disease of the newborn [HDN] which is now routinely prevented by the administration of polyclonal anti-D immunoglobulin. This management of HDN has proven to be one of the most successful cases of prophylactic treatment based on antibody mediated immune suppression [AMIS]. Despite the increasing efficiency of treatment, the mechanism of action of anti-D is not completely defined. There is a widespread interest in obtaining a reliable therapeutic monoclonal anti-D, due to difficulty of maintaining a pool of high titer volunteer donors for plasma collection and also increasing demand for antenatal prophylaxis and safety issues with plasma derived products. Candidate monoclonal anti-D preparations should demonstrate appropriate functionality in both in vitro and in vivo assays comparable to polyclonal anti-D immunoglobulin. These criteria are reviewed in addition to the factors regulating development of D specific immune response in D negative individuals and its suppression in HDN prophylaxis

Eficacia de la fenotipificación Rh / Effectiveness of Rh fenotipification

Basándonos en garantizar la calidad de los procedimientos del laboratorio pretransfusional, se evaluó la eficacia de la fenotipificación Rh en donantes y receptores. Para ello se comparó el número de pacientes sensibilizados transfundidos con glóbulos rojos desplasmatizados (GRD) con fenotipo Rh tomados al azar en relación con pacientes sensibilizados transfundidos con GRD isofenotipo, a fin de determinar si la implementación de las técnicas de fenotipificación Rh en dadores y receptores disminuye la sensibilización por este sistema. De los 113 anticuerpos hallados, 65 (57,52 por ciento) corresponden al sistema Rh y 48 (42,48 por ciento) a otros sistemas de antígenos eritrocitarios. Dentro de los 65 anticuerpos del sistema Rh, 56 (86,15 por ciento) pertenecen al primer grupo y 9 (13,85 por ciento) al segundo. A través de esta casuística demostramos que la implementación de la fenotipificación Rh disminuyó la sensibilización a este sistema.

In order to guarantee the quality of procedures in the pretransfusional laboratory, RH fenotipification efficiency was analised in donors and recipients. To do this, the number of sensitized patients transfusioned with red cells (GRD) with fenotype Rh taken at random was compared with patients transfusioned with fenotype GRD, in order to determine whether the implementation of RH fenotipification techniques in donors and recipients diminishes the sensitization by this system. Out of 113 antibodies found, 65 (57,52 per cent) correspond to Rh system and 48 (42,48 per cent) to other systems of antifungals red cells. Within the 65 antibodies of the Rh system, 56 (86,15 per cent) belong to the first group and 9 (13,85 per cent) to the second. Through these cases, we are showing that the implementation of fenotipification Rh diminished the sensitization to this system.

Aloinmunizacion a un antigeno del sistema rh de alta frecuencia / Alloimmunization to a high frequency Rh antigen

Describimos el caso de una embarazada sensibilizada con un aloanticuerpo anti-Rh17 de muy amplia reactividad. Los glóbulos rojos de la paciente presentaban una deleción parcial de los antígenos del sistema Rh, responsable de la aloinmunización encontrada. Debido a la dificultad de obtener sangre compatible se elaboró un plan de transfusión autóloga para cubrir las posibles demandas. El análisis molecular del locus RH demostró la presencia de un alelo híbrido RHCE-D(5-7)-CE que generaba el fenotipo delecionado.

Frecuencias de grupos sanguíneos e incompatibilidades ABO y RhD, en La Paz, Baja California Sur, México / Blood group frequencies and ABO and RhD incompatibilities in La Paz, Baja California Sur, Mexico

OBJECTIVE: To determine genic and phenotypic frequencies and predict the risk of incompatibility and maternal alloimmunization in the population of La Paz. MATERIAL AND METHODS: This descriptive study evaluated 1809 voluntary blood donors attending in 1998 the Hospital General de Zona of Instituto Mexicano del Seguro Social (Zone General Hospital of the Mexican Institute of Social Security) in La Paz, Baja California Sur, Mexico. Blood donors were typified by tube agglutination. The gene frequencies were estimated assuming equilibrium conditions, and incompatibilities and alloimmunization were statistically assessed with the chi 2 test. RESULTS: Percent frequencies were as follows: blood group O, 58.49; A, 31.40; B, 8.40; AB, 1.71; RhD, 95.36; and RhD negative, 4.64. Genic frequencies were: i, 0.7648; IA, 0.1821; IB, 0.0519; D, 0.7845; and d, 0.2155, respectively. Incompatibilities between couples and mother-child were 0.3023 and 0.1685 for ABO, 0.0442 and 0.0364 for RhD, and 0.0134 and 0.0061 for double incompatibility, respectively. The probability of maternal alloimmunization was estimated at 0.0309. CONCLUSIONS: The O and RhD groups were the most common in La Paz, although frequencies were among the lowest in Mexico, contrary to the case of A and RhD negative groups. The probabilities of maternal alloimmunization and of incompatibilities were also high. Ancestral white, black, and indigenous groups admixed in the northwestern part of Mexico; after migrating to Baja California Sur the admixture of the population probably became similar to that of the remainder of the northwestern area.

Experiencia preliminar en el uso del doppler de arteria cerebral media fetal en madres RH negativas sensibilizadas / Preliminar experience in the use of doppler of fetal medial cerebral artery in alloinmumized mothers to negative rhesus factor

Se presentan 4 pacientes aloinmunizadas al factor Rh, en las cuales se efectuó seguimiento con ultrasonido Doppler color midiendo el flujo máximo de la arteria cerebral media con el propósito de evaluar anemia fetal, técnica de menor riesgo que la amniocentesis. Los 4 casos presentaron valores normales, lo que correlacionó con un buen resultado perinatal. Es necesario aumentar la casuística para poder validar el método

Role of HLA antigens in Rh (D) alloimmunized pregnant women from Mumbai, Maharashtra, India.

Immunogenetic studies in various diseases provide potential genetic markers. We have studied the incidence of HLA A, B, C, DR and DQ loci antigen in Rh (D) antigen isoimmunized mothers compared to those nonimmunized isoimmunized Rh negative mothers. Seventy six mothers who were immunized to Rh (D) antigen due to pregnancy (responders) and fifty four mothers who did not develop Rh (D) isoimmunization despite positive pregnancies (nonresponders) were selected for the study. Standard methods of serological HLA typing, ABO and Rh (D) groups, and screening for Rh D antibodies were used. 392 unrelated individuals from the population were compared as controls. In addition 45 unrelated individuals from the same population were typed for HLA DRB and DQB gene using PCR-SSP kits. The genotype frequencies of HLA A2, A3, A28, B13, B17, B35, B52, B60, Cw2, Cw6, DR4, and DQ3 were significantly increased, while the frequencies of the HLA A11, A29, A31, B7, B37, B51, Cw1 and DR9 were decreased in the responder women when compared to the non-responder women. HLA A30 (19) split antigen was not identified in immunized women while HLA A23 (9) split antigen was not identified in non immunized women. HLA A3, B17, Cw2 and DR4 showed a significant relative risk among the immunized responder women. When compared with Rh immunized women (responders) reported from USA, England and Hungary the phenotype frequencies of HLA A11, A24, A28, B5, B17, B40, DR2 and DR5 were increased while HLA A23, B8, B18, and DR6 were decreased in the Indian Rh immunized women. Two locus haplotype frequency analysis observed among the responders women revealed that among the significant haplotypes expressed A2-B5, B7-Cw1, DR2-DQ1 were highly significant haplotypes in positive linkage, while A1-B5, and A1-B7 were in significant negative linkage disequilibrium. The haplotype frequencies were <or= one when these common hapoltypes were compared with control population. Thus in the present study it is evident that the inheritance of HLA A3, B17, Cw2 and DR4 increases the relative risk factor by 2.6 times among Indian Rh isoimmunized women. Further, it is evident that there are significant differences in the observed HLA antigen frequencies and two locus haplotypes in Rh isoimmunized women when compared to women from USA, UK and Hungary due to extreme HLA polymorphism in different populations of the world.

Autoimmune Hemolytic Anemia Predominantly Associated with IgA Anti-E and Anti-c

A patient with warm autoimmune hemolytic anemia (AIHA) due to predominance of immunoglobulin A (IgA) with an Rh specificity, considered to be the first case in Korea, is described. A 13-yr-old male patient with severe hemolytic anemia showed a weak reactivity (1+) in the direct antiglobulin test (DAT) by using anti-IgG antiglobulin reagent. This finding, however, could not fully explain the patient's severe AIHA. When anti-IgA reagent was used for the DAT, strong reactivity (4+) was observed and free anti-E and anti-c autoantibodies were also detected by anti-IgA and anti-IgG reagents. The patient's hemoglobin began to rise with the administration of steroids. Because RBCs coated with multiple types of immunoglobulins are associated with more severe hemolysis than those only with IgG, the DATs using anti-IgA and other reagents are needed for the correct diagnosis when the result of DAT is not compatible with patient's clinical manifestations.

Estudio genético multiloci en la población colombiana I. Desequilibrio de ligamento para el sistema CcEe / Genetics study

Una muestra de 11.113 individuos de la población colombiana, caracterizados para el sistema sanguíneo Rh con los sueros anti-C, anti-c, anti-E y anti-e, se distribuyeron en diez regiones de acuerdo con su lugar de nacimiento y dos generaciones, padres e hijos; se estimó el desequilibrio de ligamiento por el método del haplotipo para el sistema CcEe. Todos los valores de desequilibrio calculados fueron negativos y altos, debido a la baja asociación encontrada de la gameta CE; además, en todas las regiones y en la población total para las dos generaciones, se encontró que el valor de desequilibrio es cercano al máximo valor de desequilibrio posible

Evaluation of a modified IRMA for anti-D quantitation, using 3H protein A.

A modified immunoradiometry assay (IRMA) using tritiated (3H) protein A was developed to estimate anti-D concentration. The main advantages of the assay were longer shelf life of the labelled reagent (more than two years); minimum radiation hazard and; low non specific binding. Levels of anti-D were estimated in 23 Rh (D) immunised women. A good correlation of anti-D concentration (micrograms/ml) with Rh antibody titre was observed (r = +0.89, P < 0.01). Anti-D concentration estimated by 3H protein A IRMA correlated well with the severity of Rh-HDN. This assay could quantitate anti-D in sera having exclusively IgG3 subtype.