The prenatal intervention of pregnancy complicated with anti-Kell isoimmunization: a review

Hemolytic disease of the fetus and newborn-a perspective of immunohematology

BACKGROUND

Hemolytic disease of the fetus and newborn is a public health problem caused by maternal-fetal incompatibility; no prophylaxis is available for most alloantibodies that induce this disease. This study reviews the literature regarding which antibodies are the most common in maternal plasma and which were involved in hemolytic disease of the fetus and newborn.

METHOD

Seventy-five studies were included in this review using a systematic search. Two independent authors identified studies of interest from the PubMed and SciELO databases.

MAIN RESULTS

Forty-four case reports were identified, of which 11 babies evolved to death. From 17 prevalence studies, the alloimmunization rate was 0.17 % with 161 babies receiving intrauterine transfusions and 23 receiving transfusions after birth. From 28 studies with alloimmunized pregnant women (7616 women), 455 babies received intrauterine transfusions and 21 received transfusions after birth.

CONCLUSION

Rh, Kell, and MNS were the commonest blood systems involved. The geographical distribution of studies shows that as these figures vary between continents, more studies should be performed in different countries. Investing in early diagnosis is important to manage the risks and complications of hemolytic disease of the fetus and newborn.

The role of measuring peak systolic velocity of the middle cerebral artery blood flow and anti-K1 titre during pregnancy to detect foetuses with severe anaemia, foetal hydrops, and the requirement of intrauterine transfusion: A systematic review and meta-analysis

The clinical manifestation of foetal anaemia caused by maternal Kell alloantibodies differs from that caused by non-Kell alloantibodies. Severe anaemia develops in the foetus in the early weeks of gestation; therefore, proper management and early intervention are important. A systematic review and meta-analysis was performed to determine whether the anti-K1 titre can determine the sequelae of Kell alloimmunised pregnancies. Prospective and retrospective cohort studies were used to conduct a systematic review following a comprehensive literature search, in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Studies were screened based on a defined set of inclusion and exclusion criteria. A total of 5143 potential articles were identified. Ten studies were used in the meta-analysis of pregnancy outcomes for a specific anti-K1 titre cut-off. The meta-analysis identified statistical significance for intrauterine transfusion (ARD: 0.351; 95 % CI: 0.593-0.109; p-value = 0.004), hydrops (ARD: 0.808; 95 % CI: 1.145-0.472; p-value <0.001), intrauterine foetal death (ARD: 0.938; 95 % CI:1.344 to -0.533; p-value <0.001) and intrauterine transfusion for Doppler middle cerebral artery >1.5 MoM (ARD: 0.381; 95 % CI:1.079 to -0.317; p-value = 0.285). It was concluded that there is no correlation between anti-K1 titre and Kell sensitised pregnancy outcomes, but monitoring the anti-K1 titre is important to manage the pregnancy and it helps clinicians determine the need for intrauterine transfusions. Doppler middle cerebral artery peak systolic velocity is strongly correlated with foetal anaemia and is an efficient routine method for determining the need for intrauterine transfusions in pregnancies affected by anti-K1.

Successful management of severe Kell alloimmunization in pregnancy with intravenous immune globulin

Hemolytic Disease of the Fetus and Newborn (HDFN) is a condition that affects 1 to 2 out of 1000 patients during pregnancy (1). When an alloantibody is present, it is essential to identify its nature in order to organize appropriate follow-up. Kell-mediated HDFN is rare; it occurs in about 5% of Kell alloimmunized pregnant women. It is important to note that in case of anti-Kell immunization, the severity of HDFN is not correlated with maternal antibody titers, and anemia tends to occur earlier and more severely. Therefore, early diagnosing and management of this condition is crucial. In the management of severe fetal anemia due to Kell immunization, available treatments include in utero transfusion (IUT), immunoglobulin therapy. Other alternative treatments exist, such as plasmapheresis. Intravenous immunoglobulin (IVIG), a noninvasive therapeutic approach, acts through multiple mechanisms. IVIG has been evaluated in cases of RhD immunization with high maternal antibody titers and a history of pregnancies involving early hydrops or intrauterine death. Regarding the potential benefits of intravenous IgG therapy, it may delay the need for early IUT, reduce the overall reliance on IUT, and have a positive impact on obstetric outcomes. This case of IV IgG therapy of anti-Kell immunization offers a thought-provoking avenue for future exploration.

Alloimmune hemolytic disease of the fetus and newborn: genetics, structure, and function of the commonly involved erythrocyte antigens

Hemolytic disease of the fetus and newborn (HDFN) can occur when a pregnant woman has antibody directed against an erythrocyte surface antigen expressed by her fetus. This alloimmune disorder is restricted to situations where transplacental transfer of maternal antibody to the fetus occurs, and binds to fetal erythrocytes, and significantly shortens the red cell lifespan. The pathogenesis of HDFN involves maternal sensitization to erythrocyte "non-self" antigens (those she does not express). Exposure of a woman to a non-self-erythrocyte antigen principally occurs through either a blood transfusion or a pregnancy where paternally derived erythrocyte antigens, expressed by her fetus, enter her circulation, and are immunologically recognized as foreign. This review focuses on the genetics, structure, and function of the erythrocyte antigens that are most frequently involved in the pathogenesis of alloimmune HDFN. By providing this information we aim to convey useful insights to clinicians caring for patients with this condition.

Fetal‐placental antigens and the maternal immune system: Reproductive immunology comes of age

Reproductive physiology and immunology as scientific disciplines each have rich, largely independent histories. The physicians and philosophers of ancient Greece made remarkable observations and inferences to explain regeneration as well as illness and immunity. The scientific enlightenment of the renaissance and the technological advances of the past century have led to the explosion of knowledge that we are experiencing today. Breakthroughs in transplantation, immunology, and reproduction eventually culminated with Medawar’s discovery of acquired immunological tolerance, which helped to explain the transplantation success and failure. Medawar’s musings also keenly pointed out that the fetus apparently breaks these newly discovered rules, and with this, the field of reproductive immunology was launched. As a result of having stemmed from transplantation immunology, scientist still analogizes the fetus to a successful allograft. Although we now know of the fundamental differences between the two, this analogy remains a useful tool to understand how the fetus thrives despite its immunological disparity with the mother. Here, we review the history of reproductive immunology, and how major and minor histocompatibility antigens, blood group antigens, and tissue‐specific “self” antigens from the fetus and transplanted organs parallel and differ.