Oliver memorial lecture. Towards the conquest of Rh haemolytic disease: Britain's contribution and the role of serendipity

Trophoblast antigens, fetal blood cell antigens, and the paradox of fetomaternal tolerance

The paradox of fetomaternal tolerance has puzzled immunologists and reproductive biologists alike for almost 70 yr. Even the idea that the conceptus evokes a uniformly tolerogenic immune response in the mother is contradicted by the long-appreciated ability of pregnant women to mount robust antibody responses to paternal HLA molecules and RBC alloantigens such as Rh(D). Synthesizing these older observations with more recent work in mice, we discuss how the decision between tolerance or immunity to a given fetoplacental antigen appears to be a function of whether the antigen is trophoblast derived—and thus decorated with immunosuppressive glycans—or fetal blood cell derived.

Clinical value of different anti-D immunoglobulin strategies for preventing Rh hemolytic disease of the fetus and newborn: A network meta-analysis

BACKGROUND

Several anti-D immunoglobulin strategies exist for preventing Rh hemolytic disease of the fetus and newborn. This study systematically assessed the clinical value of those therapeutic strategies.

METHODS

The Web of Science, PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and Wanfang databases were searched for eligible studies that evaluated the value of different anti-D immunoglobulin strategies in preventing maternal anti-D antibody sensitization. Combined odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated. The network meta-analysis was conducted using Stata 14.2 and WinBUGS 1.4.3 software.

RESULTS

Twenty-four original studies involving 64860 patients were included. Among all therapeutic measures, injecting 300 μg anti-D immunoglobulin at 28 and 34 gestational weeks (antenatal 5/E) appeared to be the most effective measure for preventing maternal antibody sensitization (surface under the cumulative ranking curve [SUCRA] = 96.8%), while a single injection at 28 gestational weeks (SUCRA = 89.2%) was the second most effective. Administering no injection or a placebo (SUCRA = 0.0%) was the least effective intervention measure.

CONCLUSION

Among the therapeutic measures, antenatal 5/E appeared to be the best method for reducing the positive incidence of anti-D antibodies in the maternal serum; thus, it may be the most effective treatment for preventing fetal hemolytic disease.

Rhesus D alloimmunization in pregnancy from 1996 to 2015 in Iceland: a nation-wide population study prior to routine antenatal anti-D prophylaxis

BACKGROUND

Rhesus D (RhD) incompatibility is still the most important cause of hemolytic disease of the fetus and newborn (HDFN) worldwide. The aim of this study was to investigate the incidence, causes, and consequences of anti-D alloimmunizations in pregnancy in Iceland, prior to implementation of targeted routine antenatal anti-D prophylaxis (RAADP) in 2018.

STUDY DESIGN AND METHODS

This was a nation-wide cohort study of 130 pregnancies affected by RhD alloimmunization in Iceland in the period from 1996 through 2015. Data were collected from transfusion medicine databases, medical records, and the Icelandic Medical Birth Register.

RESULTS

Of 130 RhD alloimmunizations, 80 cases (61.5%) represented new RhD immunization in the current pregnancy. Sensitization was discovered in the third trimester in 41 (51.3%) and occurred in the first pregnancy in 14 cases (17.5%). The most likely causative immunization event was the index pregnancy for 45 (56.25%), a previous pregnancy/birth for 26 (32.5%), abortion for 3 (3.75%), and unknown for 6 women (7.5%). Higher anti-D titers were associated with shorter gestational length, cesarean sections, positive direct antiglobulin test (DAT), and severe HDFN. Intrauterine transfusion (IUT) was performed in five pregnancies (3.8%), and 35 of 132 (26.5%) live-born neonates received treatment for HDFN; 32 received phototherapy (24.2%), 13 exchange transfusion (9.8%), and seven simple blood transfusion (5.3%).

CONCLUSION

In about half of cases, RhD alloimmunization was caused by the index pregnancy and discovered in the third trimester. Thus, the newly implemented RAADP protocol should be effective in reducing the incidence of RhD immunization in Iceland in the future.

Maternal mortality in New York--Looking back, looking forward

New York City was ahead of its time in recognizing the issue of maternal death and the need for proper statistics. New York has also documented since the 1950s the enormous public health challenge of racial disparities in maternal mortality. This paper addresses the history of the first Safe Motherhood Initiative (SMI), a voluntary program in New York State to review reported cases of maternal deaths in hospitals. Review teams found that timely recognition and intervention in patients with serious morbidity could have prevented many of the deaths reviewed. Unfortunately the program was defunded by New York State. The paper then focuses on the revitalization of the SMI in 2013 to establish three safety bundles across the state to be used in the recognition and treatment of obstetric hemorrhage, severe hypertension in pregnancy, and the prevention of venous thromboembolism; and their introduction into 118 hospitals across the state. The paper concludes with a look to the future of the coordinated efforts needed by various organizations involved in women's healthcare in New York City and State to achieve the goal of a review of all maternal deaths in the state by a multidisciplinary team in a timely manner so that appropriate feedback to the clinical team can be given and care can be modified and improved as needed. It is the authors' opinion that we owe this type of review to the women of New York who entrust their care to us.

Survey on the prevention and incidence of haemolytic disease of the newborn in Italy

BACKGROUND

In 2010, the Italian Society of Immunohaematology and Transfusion Medicine (SIMTI) carried out a survey of the incidence of haemolytic disease of the newborn (HDN) and the prevention of HDN caused by anti-Rh(D) in Italian Transfusion Structures (TS).

MATERIALS AND METHODS

A questionnaire divided into the following five sections was administered: (i) types of services provided and maintenance of legally required registers, (ii) immunoprophylaxis (IP), (iii) red cell typing and searches for irregular antibodies, (iv) evaluation of foetal-maternal haemorrhage (FMH), and (v) incidence of HDN in 2010. Of the 280 TS sent the questionnaire, 176 (63%) replied.

RESULTS

A HDN register was available in 55.5% of the TS (n =91). Immunoprophylaxis with a dose of anti-D IgG was given to all Rh(D) negative and Rh(D) variant puerpera with Rh(D) positive newborns: in more than 93% of cases the dose was between 1,500 IU (300 μg) and 1,250 IU (250 μg). Antenatal IP between the 25(th) and 28(th) week was proposed by 42 TS (26%). Seventy percent of the TS (n =115) did not make any evaluation of FMH. The number of births surveyed in 2010 was 203,384, the number of Rh(D) negative pregnancies was 13,569, while anti-D antibodies were present in 245 pregnancies. There were 111 cases of HDN due to anti Rh(D) incompatibility and in 40 of these, intrauterine transfusion (n =8) or exchange transfusion (n =32) was necessary. In 94 cases HDN was due to other irregular antibodies: in 4 of these cases intrauterine transfusion was needed and in 11 other recourse was made of exchange transfusion. Finally, there were 1,456 newborns with ABO HDN of whom 13 underwent exchange transfusion.

DISCUSSION

The data collected give a picture of the incidence of HDN in Italy and of the methods of managing IP and could form the basis for an update of the SIMTI recommendations on the management and prevention of this disease.

The prevalence of maternal F cells in a pregnant population and potential overestimation of foeto-maternal haemorrhage as a consequence

BACKGROUND

Acid elution (AE) is used to estimate foeto-maternal haemorrhage (FMH). However AE cannot differentiate between cells containing foetal or adult haemoglobin F (F cells), potentially leading to false positive results or an overestimate of the amount of FMH. The prevalence of F cells in pregnant populations remains poorly characterised. The purpose of this study was to ascertain the incidence of HbF-containing red cells in our pregnant population using anti-HbF-fluorescein isothiocyanate flow cytometry (anti-HbF FC) and to assess whether its presence leads to a significant overestimate of FMH.

MATERIAL AND METHODS

Eighty-eight pregnant patients were assessed for the presence of F cells and foetal red cells by AE and anti-HbF FC. The "FMH equivalent", estimated by AE and anti-HbF FC, was calculated.

RESULTS

Thirty-six percent of the pregnant population had F-cell populations detectable by anti-HbF FC while AE detected F cells in 48% of the population. The mean estimated FMH equivalent determined by AE and anti-HbF FC was 0.59 mL (0-23.93 mL) and 0.41 (0 to 2.19 mL), respectively (p=0.012). In 3% of our population, AE overestimated the FMH by >3 mL due to the presence of an F-cell population of at least 16%.

DISCUSSION

Thirty-six percent of a prospectively evaluated group of consecutive pregnant women were found to have F-cell populations. In some patients, these findings were clinically significant as AE overestimated the degree of FMH as a consequence.

Intramuscular versus intravenous anti-D for preventing Rhesus alloimmunization during pregnancy

BACKGROUND

Antibodies to the red cell Rhesus D (RhD) antigen can be produced during pregnancy in a RhD-negative mother carrying a RhD-positive fetus, in particular following feto-maternal haemorrhage at birth or following any procedure that may cause feto-maternal haemorrhage. While the first baby is usually not harmed, these antibodies may cause haemolytic disease of the fetus/newborn (HDFN) in subsequent RhD-positive babies. RhD incompatibility is a major cause of HDFN.To reduce the risk of HDFN, anti-D is given to RhD-negative mothers at 28 or 30 weeks of pregnancy and within 72 hours of potential maternal exposure to fetal red cells. Anit-D is currently available in both intramuscular (IM) and intravenous (IV) preparations.

OBJECTIVES

To compare the efficacy and effectiveness of IM versus IV anti-D IgG in preventing RhD alloimmunization in RhD-negative pregnant women.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2012).

SELECTION CRITERIA

Randomized controlled trials, quasi-randomized trials and cluster-randomized trials comparing IM and IV anti-D for preventing RhD alloimmunization in RhD-negative pregnant women.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and assessed trial quality. Two review authors extracted data. Data were checked for consistency by both authors.

MAIN RESULTS

Two studies involving 447 (with sample sizes 14 and 432) RhD negative women were included. The studies compared IM and IV administration of anti-D prophylaxis. In both studies the women received a 1500 IU (300 microgram) dose of Rhophylac during week 28 of gestation. There was no incidence of RhD alloimmunization in either of the studies, as the sample size was insufficient for meaningful comparison of this uncommon outcome. One of the studies found that the mean anti-D IgG concentrations after IV and IM administration differed up to seven days (36.1 (2.6) ng/mL IV; 19.8 (8.7) ng/mL IM on day seven). However, from two to three weeks post-administration, the concentrations were similar for both routes of administration. None of the women involved in the studies developed antibodies against the RhD antigen.

AUTHORS' CONCLUSIONS

It appears that IM and IV administration of anti-D are equally effective. The number of included studies and the number of participants are not enough to assess whether there are any differences. Anti-D can be administered by IM or IV injection. The choice of IM or IV route of administration will depend on the available preparations, the dose to be administered and also on the patients' preferences. This review found insufficient information upon which to guide practice due to the limited number of included studies, small sample sizes and methodological limitations.

Reaction to anti-D immunoglobulin - can we manage it?

Approximately one in six women are blood group RhD negative and are offered anti-D immunoglobulin prophylaxis to prevent sensitization and decrease the risk of haemolytic disease of the newborn in subsequent pregnancies. It has been thought that anti-D is harmless, but there is a risk of anaphylaxis. We describe a case of a woman with a possible immunological reaction to anti-D in her first pregnancy. A multidisciplinary team managed her second pregnancy, offering her evidence-based advice, where available, so that she could reach an informed decision regarding administration of anti-D or not. Women value individual tailored information rather than a 'one-size-fits-all' approach.

The role of immunoglobulins in neonatal Rhesus haemolytic disease

Rhesus (Rh) isoimmunisation is the most common form of severe haemolytic disease of the newborn (HDN). The introduction of prophylaxis with anti-D Rh0 immunoglobulin (anti-D) has resulted in a marked reduction in the sensitisation of Rh-negative women and deaths attributable to Rh HDN. The sensitisation rate could be further decreased if there was strict adherence to the guidelines for administration of anti-D prophylaxis. Whether additional prophylaxis at 28 and 34 weeks of gestation would be cost effective is controversial. Intrauterine transfusions to treat fetal anaemia, postnatal exchange transfusions and phototherapy are all part of the standard management of affected individuals. Intravenous immunoglobulin given to pregnant women can reduce fetal haemolysis, and when administered to neonates with Rh isoimmunisation has been associated with a reduction in the requirement for exchange transfusion. There are, however, potential risks of immunoglobulin administration, including haemolysis due to the presence of anti-A or anti-B antibodies, allergy and the transmission of disease.

RhD isoimmunization and current management modalities

OBJECTIVE

To review the literature on current perspectives and treatment of RhD isoimmunization.

DATA SOURCES

A search was conducted on MEDLINE and CINAHL, and supplemental articles/ bulletins were obtained from cited references and the Web site of the American College of Obstetricians and Gynecologists. Recent texts also were reviewed. Key search words: isoimmunization, Rho (d) immune globulin, fetal erythroblastosis, intrauterine blood transfusions, alloimmunization.

STUDY SELECTION

Articles and comprehensive works from indexed journals in the English language relevant to key words and published after 1995 were evaluated. Historically relevant periodicals and texts were also reviewed and selected.

DATA EXTRACTION

Data were extracted and organized under the following headings: testing of the antepartum patient, antepartum treatment of isoimmunization, testing of the postpartum patient, anti-D immune globulin, antepartum anti-D immune globulin prophylaxis, other antepartum and obstetric indications for anti-D immune globulin administration, postpartum anti-D immune globulin prophylaxis, nursing implications, and future possibilities.

DATA SYNTHESIS

RhD isoimmunized pregnancies continue to contribute to worldwide perinatal and neonatal morbidity and mortality. This review describes the basic knowledge necessary to care for these pregnancies and the current management modalities.

CONCLUSIONS

The management options for RhD compromised gestations continue to evolve almost as quickly as technological advances are made. Multiple areas of research in this field have surfaced, and nurses can become valuable members of these research teams. The literature also indicates that with the available knowledge and resources, the current rate of RhD isoimmunization can be further decreased with closer adherence to proposed management guidelines by all health care professionals.

Preventing Rhesus D haemolytic disease of the newborn by giving anti-D immunoglobulin: are the guidelines being adequately followed?

OBJECTIVE

To ascertain whether anti-D immunoglobulin is being administered to Rhesus D negative women in accordance with the 1991 recommendations for its use to cover all events which may result in fetomaternal haemorrhage.

DESIGN

The notes of women delivered in 1994 were examined for compliance with the 1991 recommendations.

SETTING

Seven maternity units using a central antenatal screening service.

PARTICIPANTS

Nine hundred and twenty-two Rhesus D negative women delivered in these seven hospitals.

MAIN OUTCOME MEASURES

The prescription, dosage and indications for administration of anti-D immunoglobulin to women during pregnancy and in the puerperium.

RESULTS

Postnatal anti-D immunoglobulin was given in appropriate doses to more than 95% of women who required it. Omissions mainly arose from confusion among women who recently had received antenatal treatment with anti-D immunoglobulin. The 1991 recommendations for antenatal administration were less closely followed. Abdominal trauma was covered in only 20% of cases. An inadequate dosage of 250 i.u. was given to 25 women for antepartum haemorrhage after 20 weeks of gestation. The purpose of the Kleihauer test was sometimes poorly understood, with a 'negative' result interpreted as a reason not to give anti-D immunoglobulin.

CONCLUSION

Closer adherence to the 1991 recommendations might further reduce the incidence of Rhesus D immunisation below the current 1%. It is suggested that more careful application of the recommendations should be evaluated before considering either routine antenatal prophylaxis, or the European recommendation of a larger dose (1000-1500 i.u.), both of which would increase the requirements for this limited resource.

Human Rh monoclonal antibodies: assessment of functional activity by chemiluminescence and RhD antibody quantitation

In vitro cellular assays have been described which are capable of evaluating the interactions between sensitised red cells and monocyte or K cells. The chemiluminescence assay (CL) has several advantages over other cellular assays used to assess functional activity. The CL assay unlike the ADCC assays does not require the use of radioisotopes and therefore can be easily integrated into the work of a Reference Serology laboratory. The CL assay is an objective test and not labour intensive which is the main criticism of the monocyte monolayer assay. Seventy-four monoclonal anti-Ds and 29 other Rh specificities have been evaluated by a CL assay. The use of the chemiluminescent response produced by erythrophagocytosis of sensitised red cells has been shown to correlate well with the in vivo response to red cells sensitized with polyclonal IgG antibodies. This study aimed at investigating whether the CL assay could identify and differentiate monoclonal antibodies that are capable of eliciting a response from human monocytes. Poor correlation was obtained between the CL assay results and anti-D quantitation (r = 0.236). The chemiluminescence assay discriminated between anti-D's with high quantitation levels but low predicted functional activity and anti-Ds of low quantitation levels which produced elevated CL responses. Only 3 of the 29 non-Rh D specificities tested produced a response in the CL assay emphasising the importance of specificity in the functional activity of monoclonal antibodies. The demonstration of significant differences in the functional capabilities of monoclonal antibodies has important implications for reviewing the possible use of monoclonal anti-D preparations for Rh immune prophylaxis and highlights the requirement for factors other than the antibody concentration to be examined.