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PubMed1990

Major histocompatibility complex markers and red cell antibodies to the Rh (D) antigen. Absence of association.

Between 20 and 35 percent of Rh(D) antigen-negative individuals do not develop antibodies to D even after multiple transfusions of Rh-positive red cells. To evaluate the possibility that antibody production after exposure to the D antigen was related to a major histocompatibility complex immune response gene, analysis of the HLA genotypes of 38 Rh-sensitized women and their families was performed. No significant deviations were found in the frequency of any individual HLA class I, II, or III allele or of any extended haplotype (fixed allelic combinations of HLA-B, HLA-DR, and the complement components BF, C2, C4A, and C4B). Type 1 errors due to the extreme allelic polymorphism of the HLA system, as well as the ethnic variation in patient groups, may have contributed to HLA allele-antibody responder relationships reported in earlier studies.

Female↗
PubMed1991

Hemolytic disease of the newborn caused by anti-Rh32 and demonstration that RN encodes rhi (Ce,Rh7).

A family is described in which the mother made anti-Rh32 as a result of pregnancy; her second liveborn child had hemolytic disease of the newborn and required an exchange transfusion. In investigating the family, it was found that the father's RN gene did not make rhi and that his second Rh gene made normal amounts of c and e but a reduced amount of f. In the two children of the couple, who inherited a normal r or Ro from their mother, the paternally derived RN encoded an amount of rhi that could be detected in direct typing tests. In the father, lack of production of rhi by RN may have represented a suppressive effect of the ce(f) gene in trans to RN or the presence of an unlinked suppressor of Rh that might also have been responsible for the reduced production of f by his r or Ro gene. The two children in this family are the first persons in whom RN has been shown to make rhi.

Erythroblastosis, Fetal↗
PubMed1991

Detecting fetomaternal hemorrhage: a comparison of five methods.

Appropriate postpartum administration of Rh immune globulin relies on sensitive detection and accurate quantitation of fetomaternal hemorrhage (FMH). Recently, the microscopic Du test (micro Du) enhanced with polyethylene glycol (PEG Du) and flow cytometry (FC) have been advocated for this purpose. Three qualitative methods (micro Du, rosette test, and PEG Du) and two quantitative methods (acid elution and FC) for assessing FMH were evaluated with particular attention given to PEG Du and FC. In vitro studies comprised 10 series of dilutions of D+ cord cells in D- adult cells to yield D+ cell concentrations of 0.06, 0.12, 0.25, 0.50, 0.75, 1.0, and 2.0 percent. Additionally, 26 postpartum samples were tested. Of the qualitative techniques, the micro Du test was the least sensitive with 20 percent false-negative results occurring at 0.5 percent fetal cells. The PEG Du test was only slightly more sensitive and offered no clinical advantage. The rosette test was the most sensitive, consistently detecting fetal cells at concentrations of 0.25 percent or greater. FC and acid elution showed similar results, with good correlation obtained between measured and expected quantities of fetal cells (r = 0.99 and 0.96, respectively). One of 26 postpartum samples was positive by all screening techniques; acid elution and FC detected 0.3-percent concentrations of fetal cells and 0.17-percent concentrations of D+ cells, respectively. Although acid elution is a more commonly used method for quantitating FMH, FC offers an acceptable alternative that is capable of analyzing large numbers of cells with objectivity and reproducibility.

Coombs Test↗
PubMed1994

The risk of alloimmunization to c (Rh4) in R1R1 patients who present with anti-E.

BACKGROUND: Because the Rh antigens E (Rh3) and c (Rh4) are relatively immunogenic, it has been suggested that R1R1 (E-, c-) patients who present with anti-E alone receive prophylactic c- (Rh: -4) red cell transfusions. STUDY DESIGN AND METHODS: To determine the utility of this approach, the transfusion records of 100 consecutive R1R1 patients with anti-E identified over a 6-year period were reviewed. RESULTS: Thirty-two (32%) had anti-c concurrent with anti-E. Twenty-seven of the 68 patients who presented with anti-E alone received random (i.e., not typed for c [Rh4]) red cell transfusions. Five (18.5%) of the 27 subsequently developed anti-c 13 to 193 days (mean, 50) after transfusion of 2 to 14 (mean, 8) red cell units. None of the five had clinical evidence of hemolysis that could be attributed to a delayed hemolytic transfusion reaction. Twenty-two (81.5%) of the 27 failed to develop anti-c even after transfusion of 1 to 41 (mean, 9; median, 7) red cell units. CONCLUSION: The overall rate of immunization to c (Rh4) antigen in R1R1 patients with anti-E was 37 percent. Production of anti-c following transfusion to R1R1 patients with anti-E occurred in 18.5 percent of the cases in this series, which could have been avoided by the prophylactic use of R1R1 (E-, c-) blood for transfusion. The prophylactic use of c- (Rh: -4) blood in this patient population may be justified by the high immunization rate and the potential risk of delayed hemolytic transfusion reaction.

Adult↗
PubMed1996

Flow cytometric quantitation of serum anti-D in pregnancy.

BACKGROUND: The major cause of fetal hemolytic disease is maternal immunization to D in D-incompatible pregnancies. To prevent complications, D-incompatible pregnancies are monitored for the level of maternal anti-D. At present, the monitoring of anti-D levels is performed by the indirect antiglobulin test complemented by quantitation by the technique used in an automated antibody detection and quantitation instrument. STUDY DESIGN AND METHODS: Flow cytometry was used to quantitatively determine the level of anti-D in serum and to analyze the IgG subclass distribution and the presence of IgM anti-D in these samples. The results were compared to the indirect antiglobulin test titer and to the results obtained by the technique used in an automated antibody detection and quantitation instrument. RESULTS: Flow cytometry allowed sensitive and accurate determinations of anti-D levels with low interassay and intra-assay variability, both for serum samples and standard curves. CONCLUSION: Flow cytometry is a simple, rapid, and reliable method for determining the serum levels of D antibodies and their Ig subclass distribution. It is therefore well suited for the monitoring of women during D-incompatible pregnancies.

Female↗
PubMed1997

Differentiation of anti-D, -C, and -G: clinical relevance in alloimmunized pregnancies.

BACKGROUND: The differentiation of anti-D, -C, and -G specificities is seldom considered clinically important in pretransfusion testing. However, distinguishing these antibody specificities in alloimmunized pregnancies may be essential. The clinical prognosis as well as Rh immune globulin prophylaxis depends on the accurate identification of these antibodies. CASE REPORT: A pregnant woman, para 1 gravida 4, who had received Rh immune globulin at appropriate intervals during her previous pregnancies was reported to have anti-D (titer = 4) and anti-C (titer = 32). Differential adsorption and elution studies showed that the patient had anti-C and anti-G, but not anti-D. This case prompted retrospective examination of the sera from six other women with anti-D and anti-C who were referred to a high-risk pregnancy clinic. Of six pregnant women reported to have anti-D and anti-C; two had anti-D, -C, and -G; three had anti-D and -G, but not anti-C; and one had anti-C and -G, but not anti-D. This last is similar to the index case. CONCLUSION: Cases of pregnant women with anti-C and -G, but not anti-D, are not infrequent. Studies to differentiate anti-D, -C, and -G should be performed on alloimmunized pregnant women presumptively identified as having anti-D and anti-C when the medical history (Rh immune globulin prophylactic therapy) and/or titer values (e.g., anti-C titer higher than anti-D titer) suggest that anti-D may not actually be present. Rh immune globulin has not failed in these patients, and they should receive this therapy during pregnancy to prevent immunization to D.

Duffy Blood-Group System↗
PubMed1999

Evaluation of a panel of human monoclonal antibodies to D and exploration of the synergistic effects of blending IgG1 and IgG3 antibodies on their in vitro biologic function.

BACKGROUND: The D immunoprophylaxis program has successfully reduced the incidence of Rh hemolytic disease of the newborn (HDN), but it has also reduced the availability of plasma-derived polyclonal anti-D, which constitutes the current therapeutic product. Human monoclonal anti-D from hybridoma cell lines may be an acceptable alternative, and clinical efficacy of each anti-D is being evaluated in several centers. STUDY DESIGN AND METHODS: This study represents the largest assessment (outside of the International Workshops) of human D monoclonal antibodies for potential therapeutic use. The in vitro biologic activity and immunologic and serologic reactivity of a coded panel of 20 D antibodies (THERAD) was investigated. The bioassays used were lymphocyte (K-cell) antibody-dependent cell-mediated cytotoxicity (ADCC), monocyte ADCC, and monocyte chemiluminescence, which together reflect the processes involved in antibody-coated red cell destruction in vivo. From this panel, six antibodies (THERADs 14, 19, 22, 23, 27, and 28, comprising 3 IgG1 and 3 IgG3 D monoclonal antibodies) were further selected to investigate the effects of blending in the three bioassays. RESULTS: Several THERAD blends displayed greater activity than their component parts, in the range of 6 to 124 percent. There was no evidence to suggest functional blocking effects with this restricted panel of antibodies. CONCLUSION: The THERAD blends containing both IgG1 and IgG3 anti-D appeared to be the most functionally active, as did blends containing antibodies to two distinct D epitopes. This in vitro evidence has important implications for the future formulation of an effective monoclonal preparation for the prevention of Rh HDN.

Antibodies, Anti-Idiotypic↗
PubMed1999

Male fetuses are particularly affected by maternal alloimmunization to D antigen.

BACKGROUND: It is hypothesized that male fetuses are more severely affected by fetomaternal alloimmunization to D antigen than female fetuses. STUDY DESIGN AND METHODS: One hundred four consecutive pregnancies with single D+ fetuses (51 males, 53 females) and maternal anti-D titers >16 were analyzed retrospectively. RESULT: Sixty fetuses (58%) received intrauterine transfusions. Male fetuses required more transfusions than females (5.0 vs. 2.0, p = 0.0001). At the initial transfusion, male fetuses had a lower gestational age (24.5 vs. 31.0 weeks, p = 0.0007), cord blood hemoglobin content (6.45 vs. 8.75 g/dL, p = 0.01), and hematocrit (19.8 vs. 26.8%, p = 0.004) than female fetuses. After adjustment for maternal gravidity, parity, and history of affected offspring, the odds ratio for development of hydrops by male fetuses was 13.1 (95% CI 2.69-63.6, p = 0.001). Perinatal mortality was higher in male (18%) fetuses than in female (6%) (adjusted odds ratio for males 3.38; 95% CI 0.59-19.46, p = 0.17). CONCLUSION: Male fetuses are particularly affected by maternal alloimmunization to D and require more intense antepartum surveillance than female fetuses.

Adult↗
PubMed2003

Absence of D- alloimmunization in AIDS patients receiving D-mismatched RBCs.

BACKGROUND: More than 80 percent of D- patients who receive D+ blood become alloimmunized to the D antigen. Anemia occurs in most AIDS patients at some point in the disease. D- patients with AIDS may require blood transfusion and, during times of blood shortage, may receive D+ RBCs. They would be expected to become alloimmunized to the d antigen. STUDY DESIGN AND METHODS: The records of the transfusion service between January 1996 and July 2000 were reviewed for D- patients who received D+ blood. IATs were performed before the initial transfusion and subsequently when the patient required further RBC transfusion. RESULTS: Eight D- AIDS patients who received multiple transfusions (three women and five men; age range, 31-44 years; mean, 44 years) who received between 2 and 11 units (mean, 6.25) of D+ RBCs were identified. Antibody screens were performed at 8 to 65 weeks after transfusion. It was found that none of the eight D- AIDS patients developed anti-D. ABO antibodies were found as expected. During the same period, it was found that six D- patients admitted with other diagnoses who received 1 to 9 units of D+ RBCs, all developed anti-D within 7 to 19 weeks of transfusion. CONCLUSION: Patients with AIDS may not form alloantibodies to the D antigen. This may be attributable to their immunodepressed state, particularly to the decrease in CD4+ T lymphocytes. Therefore, during blood shortages, transfusion of D+ blood to D- AIDS patients may be without any subsequent consequence.

ABO Blood-Group System↗
PubMed2003

Prenatal typing of Rh and Kell blood group system antigens: the edge of a watershed.

Knowledge of the molecular basis of the blood group systems has enabled the development of assays for blood group genotyping. At this time, polymerase chain reaction (PCR)-based assays validated on fetal material obtained by invasive means (chorionic villus sampling or amniocentesis) are available for all clinically relevant fetal blood groups, However, only Rh typing (D, C, c, E, and e) and K1 genotyping assays are discussed in this review. Importantly, one must remember that results of genotyping assays will not always be concordant with serological typing. Thus, the RhD genotyping assays have to be modified in response to increased understanding of the molecular biology of this blood group system. RhD typing assays should produce negative results when tested on the black RhD-negative RHD alleles, RHDpsi and r's. PCR-based assays can be used to determine paternal zygosity. For RhD zygosity testing, the real-time quantitative PCR approach and the direct detection of the hybrid Rhesus box, which is the result of the deletion of the RHD gene are available. Recently, methods for noninvasive prenatal genotyping have been investigated. The use of fetal cells circulating in the maternal circulation has been explored; however, the scarcity of circulating fetal cells has limited the use of this approach. More promising are the results obtained with RhD typing assays with cell-free fetal DNA, which is present in the maternal circulation in a concentration of 25 genomic equivalents per milliliter of maternal blood in early pregnancy increasing to 100 copies per milliliter in the third trimester, which is cleared from the circulation within a few hours of delivery. The positive predictive value of this approach is virtually 100%, but false-negative results are (infrequently) encountered. Therefore, this assay can at present only be used for screening of RhD-negative women to make the use of antenatal prophylaxis more targeted and hence more cost-effective. For the clinical management of the pregnancies of alloimmunized women, the development of a control for the presence and the amplification of fetal DNA is needed, which is at present only available in male pregnancies. Assays for the genotyping of the other Rh antigens or Kell antigens with cell-free fetal DNA have not yet been described.

Blood Group Antigens↗
PubMed2003

The clinical implications of platelet transfusions associated with ABO or Rh(D) incompatibility.

Despite the time elapsed since their development, and substantial human and economical efforts searching for alternatives, platelet transfusion, continues to be the main therapeutic measure available for the management of patients suffering from quantitative and qualitative platelet disorders. However, there are still aspects of their use that are not completely established. One of these is ABO and/or Rh(D) compatibility. A major ABO group incompatibility appears to decrease the response to a platelet transfusion, whereas a minor ABO incompatibility can be associated with, sometimes lethal, acute hemolytic transfusion reactions in the recipient. Other detrimental effects on the recipient of a minor ABO incompatibility have also been reported. In contrast, the main problem associated to a Rh(D) incompatible platelet transfusion is the development of alloimmunization of a Rh(D)-negative woman in childbearing age or younger. Factors like degree of patient immunosuppression and red blood cell content in the platelet concentrate significantly modulate the risk of alloimmunization. New clinical studies are needed to define clearly the current risk associated to ABO- and/or Rh(D)-incompatible platelet transfusions, and such defined risks would help establish the most cost effective measures to prevent the appearance of the potential complications related to platelet use.

ABO Blood-Group System↗
PubMed1988

The prognosis of Rh-affected pregnancies: an exception to the usual rule.

A patient with a homozygous marital partner had three progressively less seriously involved RH-positive babies after a fetal demise due to erythroblastosis. Only the first of the three required fetal transfusions. All were Rh genotypically identical. The case is presented for interest and to illustrate an exception to the usual rule.

Adult↗