Clinical consequences of the extremely rare anti-PP1Pk isoantibodies in pregnancy: a case series and review of the literature

Human Gb3/CD77 synthase: a glycosyltransferase at the crossroads of immunohematology, toxicology, and cancer research

Human Gb3/CD77 synthase (α1,4-galactosyltransferase, P1/Pk synthase, UDP-galactose: β-D-galactosyl-β1-R 4-α-D-galactosyltransferase, EC 2.4.1.228) forms Galα1 → 4Gal structures on glycosphingolipids and glycoproteins. These glycans are recognized by bacterial adhesins and toxins. Globotriaosylceramide (Gb3), the major product of Gb3/CD77 synthase, is a glycosphingolipid located predominantly in plasma membrane lipid rafts, where it serves as a main receptor for Shiga toxins released by enterohemorrhagic Escherichia coli and Shigella dysenteriae of serotype 1. On the other hand, accumulation of glycans formed by Gb3/CD77 synthase contributes to the symptoms of Anderson-Fabry disease caused by α-galactosidase A deficiency. Moreover, variation in Gb3/CD77 synthase expression and activity underlies the P1PK histo-blood group system. Glycosphingolipids synthesized by the enzyme are overproduced in colorectal, gastric, pancreatic, and ovarian cancer, and elevated Gb3 biosynthesis is associated with cancer cell chemo- and radioresistance. Furthermore, Gb3/CD77 synthase acts as a key glycosyltransferase modulating ovarian cancer cell plasticity. Here, we describe the role of human Gb3/CD77 synthase and its products in the P1PK histo-blood group system, Anderson-Fabry disease, and bacterial infections. Additionally, we provide an overview of emerging evidence that Gb3/CD77 synthase and its glycosphingolipid products are involved in cancer metastasis and chemoresistance.

Preoperative Autologous Blood Donation for Rh-Negative Pregnant Women Undergoing Cesarean Sections

Background

Cesarean sections (C-section) often require blood transfusions in cases of severe bleeding, particularly challenging in Rh-negative pregnancies due to the scarcity of Rh-negative donors, with only approximately 0.3% of the population in Thailand. Autologous blood donation, where individuals donate their own blood before surgery, offers a promising solution. Our study focused on preparing preoperative autologous blood donations (PAD) for Rh-negative pregnancies.

Methods

We conducted blood screening on 7,182 pregnancies at Takuapa Hospital from October 2013 to September 2018, identifying 21 Rh-negative pregnant women. We established criteria based on hemoglobin (Hb) levels, which are crucial for autologous blood preparation (Hb at 11.0 g/dL, and hematocrit (Hct) above 33%). Blood samples were collected twice during pregnancy, at 36 and 37 weeks, with the second collection 1 week before the C-section. Pregnancies testing positive for infectious markers were excluded following standard blood donation guidelines. Twelve pregnant women testing negative for infectious markers were enrolled.

Results

The demographic data showed 12 subjects aged 17 to 41 years, with an average of 27.83. Initial blood tests indicated Hb and Hct levels of 12.5 g/dL, and 36.4%, slightly decreasing to 12.2 g/dL and 35.8% in the second collection. On the day of the cesarean, levels further declined to 11.6 g/dL and 34.4%, respectively, within normal ranges. At discharge, the Hct measured 34.8%. Maternal and infant health post-C-section were good, with baby weights ranging from 2,640 to 4,080 g. None of the 12 cases required autologous blood transfusion, validating the safety of standard autologous blood preparation practices.

Conclusions

This study highlights the safety of autologous blood donation for pregnant women with rare blood types, which was achieved through effective planning and collaboration among hospital departments. These findings can serve as a model for other hospitals and significantly reduce the burden of searching for Rh-negative donors.

Successful management of maternal anti-PP1Pk alloimmunization in pregnancy with therapeutic plasma exchange and intravenous immunoglobulin

Anti-PP1PK alloimmunization is rare given ubiquitous P1PK expression. Prevention of recurrent miscarriages and hemolytic disease of the fetus and newborn (HDFN) in pregnant individuals with anti-PP1PK antibodies has relied upon individual reports. Here, we demonstrate the successful management of maternal anti-PP1PK alloimmunization in a 23-year-old, G2P0010, with therapeutic plasma exchange (TPE), intravenous immunoglobulin (IVIG), and monitoring of anti-PP1Pk titers. Twice-weekly TPE (1.5 plasma volume [PV], 5% albumin replacement) with weekly titers and IVIG (1 g/kg) was initiated at 9 weeks of gestation (WG). The threshold titer was ≥16. Weekly middle cerebral artery-peak systolic velocities (MCA-PSV) for fetal anemia monitoring was initiated at 16 WG. PVs were adjusted throughout pregnancy based on treatment schedule, titers, and available albumin. Antigen-negative, ABO-compatible RBCs were obtained through the rare donor program and directed donation. An autologous blood autotransfusion system was reserved for delivery. Titers decreased from 128 to 8 by 10 WG. MCA-PSV remained stable. At 24 WG, TPE decreased to once weekly. After titers increased to 32, twice-weekly TPE resumed at 27 WG. Induction of labor was scheduled at 38 WG. Vaginal delivery of a 2950 g neonate (APGAR score: 9, 9) occurred without complication (Cord blood: 1+ IgG DAT; Anti-PP1Pk eluted). Newborn hemoglobin and bilirubin were unremarkable. Discharge occurred postpartum day 2. Anti-PP1Pk alloimmunization is rare but associated with recurrent miscarriages and HDFN. With multidisciplinary care, a successful pregnancy is possible with IVIG and TPE adjusted to PV and titers. We also propose a patient registry and comprehensive management plan.

Glycosphingolipids in congenital disorders of glycosylation (CDG)

Congenital disorders of glycosylation (CDG) are a large family of rare disorders affecting the different glycosylation pathways. Defective glycosylation can affect any organ, with varying symptoms among the different CDG. Even between individuals with the same CDG there is quite variable severity. Associating specific symptoms to deficiencies of certain glycoproteins or glycolipids is thus a challenging task. In this review, we focus on the glycosphingolipid (GSL) synthesis pathway, which is still rather unexplored in the context of CDG, and outline the functions of the main GSLs, including gangliosides, and their role in the central nervous system. We provide an overview of GSL studies that have been performed in CDG and show that abnormal GSL levels are not only observed in CDG directly affecting GSL synthesis, but also in better known CDG, such as PMM2-CDG. We highlight the importance of studying GSLs in CDG in order to better understand the pathophysiology of these disorders.

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.

Treatment with plasma exchange of a pregnant woman with anti-PP1Pk alloimmunization: A case report

The histo-blood group antigens P, P1 and Pk are a closely related set of glycosphingolipid structures expressed by red blood cells and other tissues. None of these three characters is expressed on p cells, a null phenotype that arises in the context of homozygous mutation of the A4GALT gene. Subjects with p phenotype spontaneously develop a natural alloantibody named anti-PP1Pk, which is a mixture of IgG and IgM against P1, P and Pk. While anti-P1 is a weak cold antibody with poor clinical significance, anti-P and anti-Pk antibodies are potent haemolysins responsible for severe hemolytic transfusion reactions. The rare anti-PP1Pk alloantibodies are associated with recurrent spontaneous abortion in the first trimester of gestation. P and Pk antigens are expressed at high levels on the placenta and antibodies directed against both these structures are deleterious to placental trophoblasts. Here we describe the use of plasma exchange (PEX) in a nulliparous 39-year-old woman with anti-PP1Pk antibodies and a history of repeated spontaneous early abortions and hypofertility. The patient underwent apheresis starting from the third week throughout the pregnancy and a healthy child was delivered by cesarean section at 35 WG. The newborn required only phototherapy within a few days of life. We can state that an early treatment with the only PEX has proven to be effective and safe in the management of a fetomaternal P-incompatibility caused by a high anti-PP1Pk titer (256).

Recurrent miscarriage associated with rare anti-PP1Pk antibody: a case series and literature review.. [DOI: 10.21203/rs.3.rs-2728370/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: The anti-PP1Pk antibody is a rare antibody associated with recurrent spontaneous abortion (RSA) in the first trimester. As it is a rare entity, few reports have been published, especially in China. Currently, there is no specific treatment for RSA associated with anti-PP1Pk antibody because it is a naturally occurring antibody. This study aims to report three cases of RSA associated with the anti-PP1Pk antibody to share our experiences with its management. Methods: The three patients' medical information was obtained from the medical records. Intravenous immunoglobulin and/or plasmapheresis was offered to the patients. We also made an extension research of the related literature about RSA associated with anti-PP1Pk antibody. Results: Although patients received intervention, the maternal anti-PP1Pk antibody titer remained stable and did not decrease. There were no live births. We summarized publications about pregnancy in women with anti-PP1Pk antibodies. Conclusions: Early initiation of plasmapheresis in high-risk patients with anti-PP1Pk antibodies should be strongly considered.

Naturally occurring anti-PP1PK in a Chinese individual with p phenotype: A case based on compound heterozygosity including one novel allele

BACKGROUND

The null phenotype in P1PK blood group, known as "p," is extremely rare in the whole world. Individuals of p phenotype spontaneously form anti-PP1P^K isoantibody. Here, we report a case of p phenotype with naturally occurring anti-PP1P^K isoantibodies in a Chinese individual.

STUDY DESIGN AND METHODS

Serology tests, containing alloantibodies screening and identification, were conducted to demonstrate the phenotype in P1PK blood group. The genotype of A4GALT gene was identified by haplotypes separation and sequencing.

RESULTS

The serological assay demonstrated the p phenotype of the proband, presenting with 1:64 titer of anti-PP1P^K . The sequencing data revealed a compound heterozygote consisting of A4GALT*P1.01 with c.343A>T and a novel allele based on A4GALT*01N.05 with an addition polymorphism c.100G>A. The sequence of the novel allele has been submitted to GenBank and the accession number OM912503 was assigned.

CONCLUSION

Our study demonstrates a case of naturally occurring anti-PP1Pk in a Chinese individual with p phenotype, which is based on compound heterozygosity including one novel allele. As the proband is a young lady, monitoring the titer of anti-PP1P^K and early initiation of medical intervention are essential after her pregnancy.

First successful pregnancy outcome after twelve abortions in a Tunisian-woman with the rare p phenotype

INTRODUCTION

Anti-PP1P k alloantibody, is produced in the serum of individuals with the rare p phenotype. It is associated with severe haemolytic transfusion reactions, recurrent spontaneous early abortions as well as haemolytic disease of the foetus and newborn. Anti-PP1P k alloimmunization in pregnancy differ from others in their physiopathology. It seems that the placenta would be the main target of anti-PP1P k antibody.

CASE REPORT

This report concerns a 35 year old female, with a history of a high incidence (12) of early and recurrent miscarriages. She was found to have the extremely rare p phenotype and anti-PP1P k antibody in her serum. Her 13th pregnancy was successfully managed by plasmapheresis. No substitution fluid was added. Oral hydration was recommended before and after the apheresis sessions. 12 plasmapheresis cycles were performed before a healthy term female infant weighing 3kg600g, was delivered by caesarean section at 38 weeks of gestation.

CONCLUSION

Plasmapheresis seems to be the treatment of choice in the management of anti-PP1P k fetomaternal incompatibilities. However in this case, we opted for an original and less expensive protocol. We did resort, neither to substitution fluid nor to intravenous immunoglobulin.