Management of pregnancies complicated by anti-Kell isoimmunization

Managing a Pregnancy in the Presence of the Rare Blood Group Antibody PP1Pk

Pregnant women with p phenotype, who lack antigens P, P1, and Pk, spontaneously form anti-PP1Pk antibodies whose primary target is the placenta. The risk of miscarriage in these women is 50%-70% and reaches 87% in the second trimester. The therapies aim to reduce the titer of antibodies early in pregnancy. They also have risk of hemolytic transfusion reaction, with very few compatible red blood cell donors in the world. In this study, we present a case of successful pregnancy managed with autologous blood donations and plasmapheresis.

Alloimmunization due to red cell antibodies in Rhesus positive Omani Pregnant Women: Maternal and Perinatal outcome

OBJECTIVE

This study is aimed to determine the prevalence of alloimmunization due to antibodies to red blood cell (RBC) antigens (other than rhesus [Rh] antigen) and report the maternal, perinatal, and neonatal outcomes.

MATERIALS AND METHODS

A retrospective review of medical records of all patients with minor RBCs antibodies alloimmunization who were followed and delivered at Sultan Qaboos University Hospital, Oman from June 2011 to June 2013. Maternal characteristics, antibody type, antibody titer in addition to perinatal and neonatal outcomes were reviewed.

RESULTS

There were 1160 patients with Rh positive status in the study. The most common ABO blood group was O, followed by A, B, and AB. We found 33 out of 1160 Rh positive women alloimmunized with minor RBCs antibodies that gave a prevalence of minor RBCs alloimmunization of 2.7%. The most frequent antibody was anti-E 38%, followed by anti-c 17% and anti-kell 17%. 6 of these 33 patients were identified to have significant antibody titer, and two cases showed evidence of fetal anemia. Only one case required an intrauterine blood transfusion. The most common neonatal complication was jaundice in 53%, followed by respiratory distress syndrome in 28%. Two cases complicated by neonatal anemia required a postnatal blood transfusion.

CONCLUSION

Alloimmunization with anti-E, anti-c, and anti-kell were the most common antibodies among the study group. Minor RBCs alloimmunization was an important cause of neonatal morbidity.

Haemolytic disease of the fetus and newborn

Haemolytic Disease of the Fetus and Newborn (HDFN) is caused by maternal alloimmunization against red blood cell antigens. In severe cases, HDFN may lead to fetal anaemia with a risk for fetal death and to severe forms of neonatal hyperbilirubinaemia with a risk for kernicterus. Most severe cases are caused by anti-D, despite the introduction of antental and postnatal anti-D immunoglobulin prophylaxis. In general, red blood cell antibody screening programmes are aimed to detect maternal alloimmunization early in pregnancy to facilitate the identification of high-risk cases to timely start antenatal and postnatal treatment. In this review, an overview of the clinical relevance of red cell alloantibodies in relation to occurrence of HDFN and recent views on prevention, screening and treatment options of HDFN are provided.

Hemolytic disease of fetus and newborn due to maternal red blood cell alloantibodies in the Malay population

Background:

Maternal red blood cell (RBC) alloimmunization may lead to production of harmful antibodies that result in hemolytic disease of fetus and newborn (HDFN). There is insufficient data on the prevalence of HDFN due to RBC alloantibodies in the Malay neonatal population.

Aim:

The aim of this study was to determine the incidence of HDFN in the Malay neonatal population due to clinically significant RBC alloantibodies.

Subjects and Methods:

A cross sectional study was conducted in Transfusion Medicine Unit, Hospital Universitiy Sains Malaysia over one year period from January to December 2009. A total of 5163 Malay pregnant women who attended labor room for delivery were collected and analyzed prospectively. The blood samples were subjected to the standard immunohematological procedure for RBC antibody screening and identification using reagents of Diamed-ID Gel microtyping system. All the newborns with RBC alloantibody were investigated for the evidence of HDFN.

Results:

Thirty (0.58%) women were found to have clinically significant RBC alloantibodies. Most of the alloantibodies belonged to Rhesus (Rh) system (56.7%) where anti-E (33.3%) was the most common followed by anti-D (10.0%). Rh antibodies were the main cause of HDFN in fourteen (0.27%) neonates. Anti-D and anti-c were identified to cause moderate to very severe HDFN.

Conclusions:

With the low prevalence of clinically significant RBC alloantibodies and HDFN, routine antenatal antibody screening practice may not be advised as a routine practice at present, preferably reserved for those women of RhD negative or with history of HDFN, significantly of those attributed to anti-c.

Provision of KEL1-negative blood to obstetric patients: a 3-year single-institution retrospective review

BACKGROUND

KEL1 alloimmunization is a major cause of hemolytic disease of the fetus and newborn (HDFN). While select countries have guidelines for preventing transfusion-associated KEL1 alloimmunization, the United States does not. Beth Israel Deaconess Medical Center instituted a policy in April 2009 whereby women not more than 50 years of age on the obstetric service were transfused KEL1-negative red blood cells (RBCs). We sought to determine compliance and impact for prevention of KEL1 alloimmunization and HDFN.

STUDY DESIGN AND METHODS

All women not more than 50 years of age without anti-K transfused RBCs during an obstetric admission from April 9, 2009, to April 9, 2012, were identified (227). Adherence to policy, factors contributing to nonadherence, and subsequent impact were evaluated. For comparison, all cases of anti-K detection in women not more than 50 years of age admitted to nonobstetric services and all cases of transfusion-associated KEL1 alloimmunization in women not more than 50 years of age during the 10 years prior were identified.

RESULTS

Eighty-four percent received only KEL1-negative units. Three (1.3%) women not more than 50 years of age on the obstetric service were identified with anti-K, while 17 (1.5%) women not more than 50 years of age on nonobstetric services had anti-K detected; only five of 20 had a prior RBC transfusion. In the 10 years prior, there were 27 cases of transfusion-associated KEL1 alloimmunization in women not more than 50 years of age. There were no cases of KEL1 HDFN in either period.

CONCLUSION

Although the findings demonstrate feasibility of providing KEL1-negative RBCs to women of childbearing potential, evidence for clinical benefit is lacking. The low prevalence of KEL1 in blood donors, the lack of significant differences in alloimmunization rates, and no cases of HDFN during the study period questions the clinical benefit of such a policy.

Associations of Rhesus and non-Rhesus maternal red blood cell alloimmunization with stillbirth and preterm birth

BACKGROUND

Although the risks of adverse pregnancy outcomes associated with anti-D antibodies are well-recognized, much less is known concerning alloimmunization with other red blood cell antibodies detected during routine maternal screening. To date, most reports of adverse pregnancy outcomes associated with non-anti-D antibodies have been from small case studies. The aim of this study was to examine the associations of maternal alloimmunization with specific red blood cell antibodies and the risks of preterm birth and stillbirth in the Swedish population.

METHODS

All antibody screening, outcome and covariate data were obtained through linkages of Swedish national health and data registers. Follow-up in these population-based registers was available up to 31 December 2002. The final study sample consisted of 1,022,569 singleton births from 668,952 mothers during 1987-2002.

RESULTS

In total, 1.3% of the 1,022,569 study pregnancies were alloimmunized. In adjusted logistic regression models, compared with having no antibodies, alloimmunization with anti-D, anti-E, anti-C and anti-c was associated with increased risk of both stillbirth and preterm birth. In addition, anti-Kell was associated with increased risk of preterm birth and anti-Lea with increased risk of stillbirth. Compared with firstborn children, risk of preterm birth associated with alloimmunization was greater in subsequent births

CONCLUSIONS

In the largest study to date, alloimmunization with Rhesus, K- and -Lea red blood cell antibodies increased the risk of preterm birth and/or stillbirth. The association of anti-Lea with stillbirth was an unexpected finding. Further study of the consequences of non-anti-D alloimmunization is warranted.

Hydrops Fetalis due to Kell Alloimmunization: A Perinatal Approach to a Rare Case

Objective: While routine administration of rhesus (Rh) immunoglobulin has significantly reduced the incidence of Rh alloimmunization, maternal alloimmunization to other red cell antigens remains a contributor to perinatal morbidity and mortality. Although the Kell antigen is seen on the red cells of only 9% of the general population, attention to Kell antibodies continues to increase.

Case Report: A case of fetal hydrops was sonographically detected at 30 weeks of gestation. Antenatal tests to evaluate the fetus’s condition clearly showed that the level of hemolytic disease was critical and the baby was delivered prematurely due to fetal distress. The combination of anemia, reticulocytopenia, hydrops fetalis, and a positive indirect Coombs test suggested Kell isoimmunization. The baby was successfully treated with exchange transfusion of Kellnegative packed red cells, and was discharged on postnatal d 30.

Conclusion: The presented case of hydrops fetalis was due Kell alloimmunization that was detected during the postnatal period, and thus we plan to discuss the perinatal approach to Kell immunization.

[Kell immunization--a case report]

INTRODUCTION

The frequency of occurrence of RhD alloimmunization, due to preventive protocols, is decreased in our country, but more often there are other antigens that emerge as a cause of hemolytic disease of fetus. The most prominent is Kell antigen, which promotes specific course of disease based on an innate pathogenetic mechanism. Anti-Kell antibody production is, just as in other atypical antibodies, provoked with transfusion of incompatible blood. Except for the immune-mediated hemolysis, anti-Kell antibodies can also inhibit the function of progenitor (erytroid and megakariocyte) cell lines.

CASE REPORT

We present the case of G1P1 woman in whom a distinct fetal hydrops was sonographically detected in the 28th week of pregnancy. The results of immunological tests undoubtedly pointed to Kell immunization (anti-Kell antibody titer was more than 1:32), and antenatal tests for evaluation of fetal condition (Doppler ultrasound and CTG) clearly showed the severe form of hemolytic disease. We concluded that the fetus was in a hopeless, terminal stage of the disease, and then decided to terminate the pregnancy.

CONCLUSION

The only clinical approach to a problem of Kell alloimunization is active one. Early cordocentesis is recommended as the optimal method for evaluation of fetal condition. The clinical outcome of the fetus will strictly depend on a timely intrauterine transfusion (IUT) procedure. Prophylaxis emerges as a crucial factor in prevention of Kell-alloimmunization. It is to be considered that all females in childhood and throughout the reproductive period should take only K1-negative blood transfusion in order to decrease the incidence of Kell-alloimmunization.

Fetal anemia due to non-Rhesus-D red-cell alloimmunization

Although anti-RhD was once the major etiology of hemolytic disease of the fetus/newborn (HDFN), the widespread adoption of antenatal and postpartum Rhesus immune globulin has resulted in a marked decrease in the prevalence of alloimmunization to the RhD antigen in pregnancy. Maternal alloimmunization to other red cell antigens continues to play a role as the cause of fetal disease since no prophylactic immune globulins are available to prevent the formation of these antibodies. An increasing incidence of the Kell (anti-K1) antibody has been noted in the United States. Guidelines for intervention in cases of irregular red cell antibodies are limited by the bias of anecdotal reports in the literature in favor of severe cases of HFDN. Although most diagnostic protocols used in the management of the RhD-alloimmunized pregnancy can be applied in cases of non-RhD sensitization, Kell (K1 and K2) alloimmunization should be managed more conservatively.

Management of pregnancies complicated by anti-Fyaalloimmunization

BACKGROUND

The objective was to evaluate the management and outcome of patients with anti-Fy(a) at the Ohio State University.

STUDY DESIGN AND METHODS

A database search for patients with pregnancies complicated only by anti-Fy(a) from 1959 to 2004. Collected information included maternal testing, fetal therapy, and neonatal outcomes.

RESULTS

The final data set included 18 pregnancies in 15 women where anti-Fy(a) was the only maternal alloantibody present and the fetus was Fy(a) antigen-positive. Maternal antibody titers of at least 32 and optical density at 450 nm values in modified Liley Zone IIB or III identified all fetuses or neonates with significant hemolytic disease (2/18, 11%). No fetuses had hydrops, and there were no deaths attributed to hemolytic disease of the fetus and newborn.

CONCLUSION

Anti-Fy(a) has the potential to lead to significant fetal hemolysis. Management guidelines developed for D sensitization are appropriate for pregnancies complicated by anti-Fy(a) alloimmunization.

Fetal anaemia: diagnosis and management

Fetal anaemia can by treated by in-utero therapy, which results in a significant improvement in perinatal outcome. The important causes of fetal anaemia are rhesus alloimmunisation, kell alloimmunisation and parvovirus infection. At-risk pregnancies require serial monitoring to ensure timely intervention with intrauterine transfusion. Non-invasive testing with middle cerebral artery Doppler is becoming the monitoring modality of choice.

Use of recombinant erythropoietin for the management of severe hemolytic disease of the newborn of a K0 phenotype mother

Very few people do not express any Kell antigens on their red blood cells (K0 phenotype). They can be immunized by transfusion or pregnancy and develop antibodies against Kell system antigens. These maternal antibodies can cause severe hemolytic disease of the fetus/newborn, as a result of the suppression of erythropoiesis and hemolysis. Multiple intrauterine transfusions in the management of severe hemolytic disease have been shown to cause erythropoietic suppression as well. Recombinant erythropoietin has been successfully used in the management of late anemia of infants with Rh hemolytic disease and in 1 case of KEL1 (Kell)-associated hemolytic disease. The authors present the case of severe hemolytic disease of a newborn due to KEL5 (Ku) isoimmunization of his K0 phenotype mother. Regular intrauterine transfusions were performed to manage the severe fetal anemia (Hb 3 g/dL). A male infant was born at the 36th week of gestation having normal hemoglobin (15.8 g/dL) and developed only mild hyperbilirubinemia. On the 15th day of life, the infant's hematocrit had fallen to 27.3%, with low reticulocyte count and low erythropoietin level. The infant was managed successfully with recombinant erythropoietin.

[Kell alloimmunization in pregnancy]

INTRODUCTION

Kell alloimmunization is a rare disease, although its incidence is the highest after after anti-D alloimmunization.

METHODS

We report two recent cases and a review of the literature to describe practical management of Kell alloimmunization in pregnancy.

DISCUSSION

When an immunization against the Kell antigen was diagnosed, amniocentesis was performed at 14 weeks gestation to determine the fetal blood group. If the fetus was Kell positive, a first fetal blood sample was drawn at 17 weeks gestation in case of fetal hydrops, and at 20 weeks without fetal hydrops. The diagnosis of anemia led to in utero transfusion. A second fetal blood sample was taken at 8 to 10 days, every two weeks during the second trimester and every three or four weeks during the third trimester. Fetal well-being was assessed with weekly sonography and rates of hemoglobin decline. These measures enable adapting the frequency of fetal blood sampling.

Late onset neonatal anaemia due to maternal anti-Ge: possible association with destruction of eythroid progenitors

There have been no reports of severe haemolytic disease of the newborn (HDN) due to Gerbich (Ge) antibodies. Two babies with HDN due to anti-Ge3, both born to the same mother, are described. The anti-Ge appeared in the first pregnancy and was not detectable in the first trimester, the babies' reticulocyte and bilirubin values were not greatly elevated (similar to HDN due to Kell antibodies), and the anaemia in both cases was either not apparent or not severe until 2 to 4 weeks after birth. Ge antigens are found on glycophorins (GPs) C and D; GPC, like Kell, has been shown to be expressed early on erythroid progenitor cells. The maternal anti-Ge3 was shown to promote phagocytosis of Ge+ early erythroid progenitors by monocytes (similar to what has been reported with anti-K and K+ progenitor cells). Thus, anti-Ge3 may cause immune destruction of erythroid progenitors and possibly suppression of erythropoiesis (which would explain the reticulocyte and bilirubin values seen in both cases). Anti-Ge3 appears to be capable of causing severe HDN. We suggest that babies born to mothers with anti-Ge should have their haemoglobin concentrations monitored for signs of anaemia for several weeks after birth. Functional assays may prove useful.

Prevention and management of RhD isoimmunization

An Rh-negative woman is at risk for developing Rh isoimmunization upon exposure to RhD antigens from her Rh-positive baby through fetal-maternal hemorrhage. The incidence of Rh isoimmunization and fetal hemolytic disease has decreased substantially since Rh immune globulin was introduced in 1968. When RhD sensitization does occur, careful follow-up of these mothers and judicious intervention can result in good outcomes for most pregnancies. Both Doppler assessment of middle cerebral artery peak systolic velocity and spectral analysis of amniotic fluid at 450 nm (DeltaOD 450) are useful in the diagnosis and management of fetal anemia.

Intravenous Fetal Exchange Transfusion before 22 Weeks of Gestation in Early and Severe Red-Cell Fetomaternal Alloimmunization

OBJECTIVES

To determine the perinatal outcome in severe red-cell fetomaternal alloimmunization.

METHODS

Retrospective series of 32 affected fetuses treated with intravenous fetal exchange transfusion (IFET) before 22 weeks of gestation. The main outcome measures were the degree of fetal anemia, fetal transfusions and perinatal outcome.

RESULTS

The first IFET was performed at 19.8 +/- 1.8 weeks of gestation. All fetuses were severely anemic and hemoglobin levels were not different between 20 hydropic and 12 nonhydropic fetuses (4.1 +/- 2.5 vs. 5.6 +/- 2.8 g/dl, p=0.33). The initial maternal anti-D level ranged from 4 to 76 microg/l and was not correlated to fetal anemia (r=-0.07).

CONCLUSION

The overall perinatal survival rate was 78% compared to a previous perinatal loss rate excluding first pregnancies of 55.5%.

Testing for hematologic disorders and complications

This review summarizes state-of-the-art and emerging techniques in the antenatal diagnosis of fetal anemia and hemoglobinopathies. Fetal anemia may result from hemolytic disease, hemorrhage, suppression of erythropoiesis, infection (eg, parvovirus B19), or trauma. The clinical laboratory plays an essential role in the evaluation of these disorders by way of the use of various hematologic, biochemical, serologic, cytometric, and molecular genetics methods. Hemoglobinopathies are the most common class of single gene disorders worldwide. The authors have used the example of homozygous alpha-thalassemia major (Hb Barts disease) as a paradigmatic case for antenatal hemoglobinopathy screening. Perhaps the most familiar indication for hematologic screening in pregnancy is HDFN, most commonly in pregnancies previously sensitized to the RhD antigen. All pregnant women, regardless of their past medical or obstetric history or previous antibody screens, should have ABO/Rh blood typing and a red cell antibody screen performed at the first prenatal visit. Long-established methods for assaying FMH (KB method), microcytosis (hemogram with red cell indices), and blood group incompatibility (direct antigen test, serologies) remain critical for rapid, sensitive diagnosis. Analysis of fetal free DNA in maternal plasma holds the promise for rapid, ultrasensitive, and noninvasive detection of many fetal hematologic disorders.

Kell expression on myeloid progenitor cells

Kell is one of the major human red blood cell groups and comprises 22 antigens. These antigens are produced by alleles located on chromosome 7, including sets of antithetical antigens such as Kell (K, K1) and cellano (k, K2), which differ in a single amino acid change (T193M). It consists of a 93-Kd transmembrane glycoprotein that is surface-exposed and shares sequence and structural homology with zinc endopeptidases, which are involved in regulating bioactive peptides. Anti-Kell antibodies have been shown to suppress fetal erythropoiesis. Recently published data indicate a similar effect on myeolopoiesis and megakaryopoiesis. Substantial thrombocytopenia in fetuses affected with HDN due to anti-K antibodies led to the discovery of the inhibitory effect of Kell-related antibodies on CFU-MK growth. In addition to its inhibitory effect on BFU-E growth, anti-Kell antibodies significantly reduced CFU-GM colony formation from haematologically normal individuals. Moreover, anti-cellano and anti-Kp(b) antibodies also inhibited the growth of CFU-GM from antigen positive MNC. These data indicate that Kell is not restricted to erythroid blood cells, but is expressed on a broader spectrum of haematopoietic cells than previously believed.

Quantitative determination of anti-K (KEL1) IgG and IgG subclasses in the serum of severely alloimmunized pregnant women by ELISA

BACKGROUND

Severe cases of HDN occur after the immunization of the mother with K (KEL1) antigen. To date, the only means of evaluating the concentration of anti-K in maternal serum is by titration with an indirect antiglobulin test (IAT). A more accurate estimation of the serum anti-K concentration is needed.

STUDY DESIGN AND METHODS

An ELISA technique was developed for the determination of the absolute concentration of anti-K IgG and IgG subclasses in the sera of alloimmunized patients. In this technique, after absorption of anti-K on K-positive RBCs and subsequent elution at acid pH, the concentration of anti-K in the eluate was measured with a sensitive and reproducible ELISA. This method was validated with monoclonal and polyclonal anti-K. It was then used to assay the sera of eight pregnant women with anti-K immunization, associated with early fetal anemia (Hct, 7-17%) detected between the 20th and the 31st week of pregnancy. In addition, in most of these cases, the anemia was associated with fetal hydrops.

RESULTS

The anti-K IgG concentration measured by ELISA in the sera of the eight women varied from 1.0 to 4.1 microg per mL (mean, 2.2 microg/mL). Therefore, severe and early forms of fetal anemia can be observed with a relatively low concentration of anti-K (as compared to the concentration of anti-D in similar cases of fetal anemia due to anti-D). The mean proportion of each IgG subclass of anti-K in these sera was IgG1, 95.9 percent; IgG2, 2.4 percent; IgG3, 1.3 percent; and IgG4, 0.4 percent.

CONCLUSION

A simple method for quantitative estimation of anti-K in human serum has been developed. Low concentrations of anti-K can cause fetal anemia relatively early in pregnancy. This method should lead to a better identification of pregnant women whose fetuses are at risk for severe fetal anemia due to anti-K.

The outcome of pregnancy in Kell alloimmunisation

OBJECTIVE

To assess management and outcome of pregnancies with anti-Kell in the West Midlands in the UK over 13 years.

DESIGN

A retrospective review of casenotes.

SETTING

A regional referral clinic for red cell alloimmune disease and fetal medicine unit at a university hospital.

POPULATION

Sixty-five pregnancies were identified in 52 Kell-sensitised women with Kell positive partners from the records of the Birmingham Blood Transfusion Centre.

METHODS

Information from the casenotes was entered on a database and comparisons were made using the SPSS for Windows statistics package.

MAIN OUTCOME MEASURES

Mode of sensitisation, degree of fetal or neonatal anaemia, need for transfusion, gestation at delivery, birthweight and pregnancy outcome.

RESULTS

Alloimmunisation was transfusion-related in 29 pregnancies and pregnancy-induced in 33. The cause could not be identified in three cases. There were 22 proven Kell positive fetuses, of which 18 were affected, in which alloimmunisation was pregnancy-related in 12 cases and transfusion-related in five. Antibody titres and amniotic fluid OD450 were not helpful in management. Severe or very severe disease occurred in 50% of the affected pregnancies (9/18). There was no difference in pregnancy outcome between transfusion or pregnancy induced sensitisation.

CONCLUSIONS

Anti-Kell alloimmunisation is an uncommon cause of serious anaemia in a significant proportion of affected pregnancies. There appears to be no difference between that caused by pregnancy or transfusion. Estimation of fetal haemoglobin concentration by cordocentesis is recommended, as antibody titres and amniocentesis are not helpful.