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[Transient appearance of anti-erythrocyte autoantibodies during Rh alloimmunization].

Transient appearance of anti-erythrocyte autoantibodies was demonstrated in two women in the first stages of Rh alloimmunization. Any mimicking antibodies, or concurrent autoimmune haemolytic anaemia could be reasonably discarded in both patients. These facts are discussed on the basis of polyclonal activation followed by clonal selection driven by the antigen, as a mechanism of the humoral immune response. Investigation of such cases seems of great interest in subjects with recent alloimmunization in order to assess the incidence of this phenomenon and the antigen systems involved.

Adult↗

Management of pregnancies complicated by rhesus (D) antibodies.

The management of anti-D alloimmunization is still changing. The mainstay of monitoring for severe disease is now ultrasonography. Non-Rh(D) antibodies are now a relatively common cause of alloimmune anaemia and should be looked for in all pregnancies.

Amniocentesis↗

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.

Enzyme-Linked Immunosorbent Assay↗

Maternal CW alloimmunization.

The Winnipeg Rh Laboratory has reviewed its experiences with maternal CW alloimmunization. From September 24, 1956, to March 31, 1992, 12 women with significant CW alloimmunization underwent 18 pregnancies. In 3 (4 pregnancies) the antibody, despite its strength, was 'naturally occurring' (i.e. there was no known exposure to CW-positive red cells). The remaining 9 women (14 pregnancies) had CW-positive husbands. Two had CW-negative babies and a third infant, probably CW negative, was stillborn and macerated at 43 weeks gestation. Eleven babies were CW positive and had hemolytic disease of the newborn (HDN), with antiglobulin-positive red cells. Five did not require treatment; 2 needed phototherapy only, and 4 (born between 1956 and 1963) required exchange transfusions. No anti-CW screening was carried out until 1977; thereafter it was sporadic, 11 of 51 screening red cells being CW positive in the 39-month period ending March 31st, 1992. From November 1, 1977, to March 31, 1992, 24 women (30 pregnancies, 31 conceptuses) with insignificant anti-CW alloantibodies were identified. Extrapolating these figures to the entire period from September 24, 1956, to March 31, 1992, we estimate that at least 430 women (at least 573 pregnancies) were CW alloimmunized, most of the antibodies being 'naturally occurring'. Only 2% of the conceptuses were CW positive and affected; none were severely affected. Anti-CW is relatively common, occurring in about 1 pregnant Manitoban woman in 1,100. On very rare occasions (11 times in Manitoba in 36 years and 5 months) anti-CW HDN occurs which, although not severe, may end in kernicterus with brain damage or neonatal death unless it is detected promptly and treated appropriately.

Coombs Test↗

[Specificity of antibodies formed in people with Rh-negative blood in response to administration to antigens C(rh', Rh2) and Cw(rhwf, Rh8)].

Anti-C, -Ce, -CD sera and monoclonal anti-C-antibodies with red cells varying by Rh-phenotypes comprising antigen C(w) have been studied. Four Rh-negative volunteer donors were reimmunized with antigens C and C(w). As shown by reactions of anti-C-sera, monoclonal antibodies anti-C with C(w)-positive cells, results of immunisation of the Rh-negative donors with antigen C(w) of Rh system, red cels containing Rh antigen C(w) contain also factor rh(C).

Antibody Formation↗

Mothers at risk of alloimmunization to the Rh (D) antigen and availability of gamma-globulin at the Mexican Institute of Social Security.

Hemolytic disease of the newborn develops mainly when an Rh negative (D-) mother becomes sensitized and produces anti-Rh positive (anti-D) antibodies capable of hemolysing D+ fetal erythrocytes. Maternal alloimmunization can be prevented by the administration of anti-D gamma-globulin immediately after the birth of each Rh positive child. In order to identify the frequency of prevention of alloimmunization at the Instituto Mexicano del Seguro Social (IMSS), the amount of mothers at risk of sensitization from 1985 to 1995 was estimated from Rh and ABO blood group frequencies and with the number of deliveries and abortions at the Medical Institutions. Also, information in regard to the dose of gamma-globulin units purchased by the Institute of Social Security from 1985 to 1993 was obtained. The number of mothers at risk steadily increased from 16,616 in 1985 to 21,071 in 1995, amounting to a total of 203,203 in the 10-year period, while only 120,800 gamma-globulin units were purchased in that same period. The findings in this study suggest the need to define reasonable policies for the acquisition of gamma-globulin lots to prevent alloisoimmunization of mothers at risk.

ABO Blood-Group System↗

The outcome of babies of mothers with severe rhesus incompatibility treated at Tygerberg Hospital, 1980-1993.

OBJECTIVE: To determine the outcome of babies of mothers with severe rhesus (Rh) incompatibility treated by elective delivery when the amniotic optical density at 450 nm crossed Whitfield's action line (group 1), by plasmapheresis and immunotherapy (group 2) or by means of intra-uterine intravascular transfusions (group 3). STUDY DESIGN: A retrospective study of 55 mothers and their 57 fetuses with severe Rh incompatibility at < 34 weeks' pregnancy duration. MAIN OUTCOME PARAMETERS: Number of mothers in each treatment group, prevalence of intra-uterine death, hydrops, intra-uterine intravascular transfusions, cord haematocrit, cord bilirubin, number of liveborn babies, birth weight, neonatal death, hyaline membrane disease (HMD) and exchange transfusions. STUDY POPULATION AND SETTING: All mothers and babies with severe Rh incompatibility (defined as an amniotic optical density of 450 nm in the upper and upper-mid zone on the Liley chart at < 34 weeks' pregnancy duration, previous fetal hydrops or Rh-related intra-uterine death (IUD), fetal hydrops on ultrasound or a fetal haematocrit < 30% at cordocentesis) treated at Tygerberg Hospital between January 1980 and January 1993. There were 20 fetuses each in groups 1 and 3, and 17 in group 2. RESULTS: A total of 48 babies (84%) were liveborn and of these 74% survived the neonatal period. (ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[Rh alloimmunization].

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Blood Transfusion, Intrauterine↗

[Prenatal determination of fetal RhD-positivity from the blood of the RhD-negative mother].

It is reported on a prenatal determination of fetal RhD blood group from blood of a sensitized RhD-positive mother at 11th week gestation. The result was confirmed by a subsequent amplification of fetal DNA obtained by chorionic villus biopsy. It is supposed that in sensitized pregnancies the high number of fetal RhD-positive red blood cells in maternal blood is enough to be detectable by polymerase chain reaction.

Abortion, Induced↗

[Rhesus prophylaxis--history and current status].

The varying symptoms of rhesus incompatibility were recognized and described approximately sixty years ago. Jörg Schneider, then at the Freiburg University Hospital in Germany, had been the very first investigator to perform rhesus prophylaxis in pregnant women. The exact date of this achievement is August 9, 1963. One year later, Schneider could report on nine women, who-following delivery of a rhesus-positive child-did not develop rhesus antibodies during a subsequent pregnancy with a rhesus-positive fetus. Since the late sixties, rhesus prophylaxis has been an integral part of prenatal care in Germany. In the meantime, the role of ante-partum prophylaxis has also been established. Since the introduction of post-partum rhesus prophylaxis, fetal morbidity and mortality has been reduced by 90 percent.

Erythroblastosis, Fetal↗

The role of the fetal immune system in the pathogenesis of RhD-hemolytic disease of newborns.

Data in the literature and author's research regarding the role of the immune reaction of fetuses and newborns in the pathogenesis of RhD conflict and hemolytic disease of newborns was analyzed. In this disease, the immune response of fetuses and newborns is shown to develop under the effects of maternal antigens, including RhD IgG, which cross the placenta. One of the results is the formation of immune complexes (ICs) between the maternal antigens and fetal IgM. In the intensive immune reaction, these ICs are removed from the infants at a high rate. As a result, the intensity of erythrocyte destruction, the degree of anemia and hyperbilirubinemia decrease. Various forms of HDN are of different intrauterine duration: from a few days in the icteric form without anemia to a month or more, in the hydropic form. In the latter form, decompensation of the immune system develops; extravascular erythroclasia by macrophages is replaced by intravascular lysis of erythrocytes. We suggest some methods to determine the fetal condition and a cure for the most severe cases of HDN, as well as a way of decreasing RhD-sensitization in women. These suggestions may be of interest to specialists in pediatrics and obstetrics and may be of clinical use.

Antigen-Antibody Complex↗

Identification of T-cell epitopes on the Rhesus polypeptides in autoimmune hemolytic anemia.

We have shown previously that the Rhesus (Rh) polypeptides are the commonest targets for pathogenic anti-red blood cell (RBC) autoantibodies in patients with autoimmune hemolytic anemia (AIHA). The aim of the current work was to determine whether activated T cells from such patients also mount recall responses to epitopes on these proteins. Two panels of overlapping 15-mer peptides, corresponding to the sequences of the 30-kD Rh proteins associated with expression of the D and Cc/Ee blood group antigens, were synthesized and screened for the ability to stimulate the in vitro proliferation of mononuclear cells from the peripheral blood or spleen of nine AIHA cases. Culture conditions were chosen that favor recall proliferation by previously activated T cells, rather than primary responses. In seven of the patients, including all four cases with autoantibody to the Rh proteins, two or more peptides elicited proliferation, but cells from eight of nine patients with other anemias and seven of nine healthy donors failed to respond to the panels. Multiple peptides were also stimulatory in two positive control donors who had been alloimmunized with Rh D-positive RBCs. Six different profiles of peptides elicited responses in the AIHA patients, and this variation may reflect the different HLA types in the group. Stimulatory peptides were identified throughout domains shared between, or specific to, each of the related 30-kD Rh proteins, but T cells that responded to nonconserved regions did not cross-react with the alternative sequences. Anti-major histocompatibility complex class II antibodies blocked the responses and depletion experiments confirmed that the proliferating mononuclear cells were T cells. Notably, splenic T cells that proliferated against multiple Rh peptides also responded to intact RBCs. We propose that pathogenic autoantibody production in many cases of AIHA is driven by the activation of T-helper cells specific for previously cryptic epitopes on the Rh proteins.

Adult↗

[Rh-D genotyping for exon 2, 5 and 7 of German and Japanese blood donors with sequence specific polymerase chain reaction].

RHD genotyping from fetal cells was applied for the detection of the RHD gene in the fetus of immunized Rh-D-negative women. Additionally, RHD genotyping was applied for the characterization of Rh-D variants. Although 44 nucleotide substitutions are known to code for 35 amino acid differences between the RHCE and the RHD gene, only a few polymorphisms have been investigated yet. We investigated 7 RHD-specific nucleotides on exons 2, 5, and 7 with sequence-specific primers and 1 nucleotide with ligation-based typing. All RHD genotyping results were correlated with serological results and established genotyping methods in 116 German and 98 Japanese blood donors, because different genetic sequences coding for Rh-D polypeptides have been described in different ethnic groups. Sequence-specific amplification of D-specific sequences was concordant with the serological result in all blood donors tested. However, ligation-based typing on exon 5 gave false-negative results in 7 donors. In summary, 5 new sequence-specific PCRs have been evaluated for further characterization of Rh-D variants. Furthermore, the methods described allow nested PCR and thus may help in determination of the fetal RhD status from maternal peripheral blood during pregnancy.

Antibodies, Anti-Idiotypic↗