Alloimmune Thrombocytopaenia Research Articles

An optimized procedure for Luminex-based human platelet antigen-specific antibody screening and identification (PakLx assay) with a cost-effective approach and improved sensitivity.

Detection of anti-platelet antibodies is required for the diagnosis of foetal/neonatal alloimmune thrombocytopaenia. The most commonly used methods for anti-platelet antibody detection are the monoclonal antibody-specific immobilization of platelet antigens (MAIPA) and the Luminex bead assay (PakLx). However, for economic reasons, the use of the PakLx assay is limited. In the present study, we evaluated the performance of an optimized protocol based on a half-volume of PakLx reagents. We compared two alternative procedures: one with a half-volume of all components including patient samples, and another based on a half-volume of reagents but a standard volume of patient sample. Our results obtained with a panel of 67 samples demonstrate improved sensitivity when using a standard sample volume. In the event of an inconclusive result with this optimized protocol (e.g., incomplete panel of positive Luminex beads), we recommend testing the sample with an alternative protocol (e.g., MAIPA or the original PakLx protocol).

The role of Australian clinical quality registries in pregnancy care: A scoping review.

BackgroundPregnancy represents a time of increased morbidity and mortality for women and their infants. Clinical quality registries (CQRs) collect, analyse and report key healthcare quality indicators for patient cohorts to improve patient care. There are limited data regarding existing CQRs in pregnancy. This scoping review aimed to: (1) identify Australian CQRs specific to pregnancy care and describe their general characteristics; and (2) outline their aims and measured outcomesMethodsThe scoping review was undertaken according to Joanna Briggs Institute guidelines. CQRs were identified using a systematic approach from publications (Ovid MEDLINE, PubMed, Google Scholar), peer consultation, the Australian register of clinical registries and web searches. Details surrounding general characteristics, aims and outcomes were collated.ResultsWe identified two primary sources of information about pregnancy care. (1) Six CQRs are specific to pregnancy (Australia and New Zealand twin‐twin transfusion syndrome registry, Australian Pregnancy Register for women with epilepsy and those taking anti‐epileptic drugs, National Register of Antipsychotic Medication in Pregnancy, Australasian Maternity Outcomes Surveillance System, Neonatal Alloimmune Thrombocytopaenia Registry and the Diabetes in Pregnancy clinical register). (2) Fourteen observational cohort studies were facilitated by non‐pregnancy‐specific CQRs where a subsection of patients underwent pregnancy.ConclusionsAustralian CQRs currently report varied information regarding some selected conditions during pregnancy and offer therapeutic and epidemiological insight into their care. Further research into their effectiveness is warranted. We note the lack of a CQR spanning the common problems of pregnancy in general, where significant health, service and economic gains are possible.

An interesting case of an atraumatic painful swollen limb in a pregnant woman

Phlegmasia cerulea dolens is an uncommon complication of deep venous thrombosis. This is associated with high rates of morbidity if not treated effectively. We present a young lady 13 weeks pregnant with one-day history of left lower limb swelling with pain and discolouration. Bedside ultrasonography revealed thrombosis occluding the common femoral vein and collateral femoral vein. She had history of neonatal alloimmune thrombocytopaenia (NAIT), and had immunotherapy previously. The safest option was to give low molecular weight heparin (LMWH) on an inpatient basis. Anticoagulation with LMWH has been well established as thromboprophylaxis during pregnancy, however, the safety profile of systemic anticoagulation is matter of debate. As highlighted in this scenario the management needs to be tailored on an individual basis. The cause for the extensive deep vein thrombosis could be possibly due to the recent immunoglobulin therapy, undiagnosed prothrombotic state (outwith pregnancy) or the procoagulant state associated with pregnancy.

Fetal stroke and cerebrovascular disease: Advances in understanding from lenticulostriate and venous imaging, alloimmune thrombocytopaenia and monochorionic twins.

Fetal stroke is an important cause of cerebral palsy but is difficult to diagnose unless imaging is undertaken in pregnancies at risk because of known maternal or fetal disorders. Fetal ultrasound or magnetic resonance imaging may show haemorrhage or ischaemic lesions including multicystic encephalomalacia and focal porencephaly. Serial imaging has shown the development of malformations including schizencephaly and polymicrogyra after ischaemic and haemorrhagic stroke. Recognised causes of haemorrhagic fetal stroke include alloimmune and autoimmune thrombocytopaenia, maternal and fetal clotting disorders and trauma but these are relatively rare. It is likely that a significant proportion of periventricular and intraventricular haemorrhages are of venous origin. Recent evidence highlights the importance of arterial endothelial dysfunction, rather than thrombocytopaenia, in the intraparenchymal haemorrhage of alloimmune thrombocytopaenia. In the context of placental anastomoses, monochorionic diamniotic twins are at risk of twin twin transfusion syndrome (TTTS), or partial forms including Twin Oligohydramnios Polyhydramnios Sequence (TOPS), differences in estimated weight (selective Intrauterine growth Retardation; sIUGR), or in fetal haemoglobin (Twin Anaemia Polycythaemia Sequence; TAPS). There is a very wide range of ischaemic and haemorrhagic injury in a focal as well as a global distribution. Acute twin twin transfusion may account for intraventricular haemorrhage in recipients and periventricular leukomalacia in donors but there are additional risk factors for focal embolism and cerebrovascular disease. The recipient has circulatory overload, with effects on systemic and pulmonary circulations which probably lead to systemic and pulmonary hypertension and even right ventricular outflow tract obstruction as well as the polycythaemia which is a risk factor for thrombosis and vasculopathy. The donor is hypovolaemic and has a reticulocytosis in response to the anaemia while maternal hypertension and diabetes may influence stroke risk. Understanding of the mechanisms, including the role of vasculopathy, in well studied conditions such as alloimmune thrombocytopaenia and monochorionic diamniotic twinning may lead to reduction of the burden of antenatally sustained cerebral palsy.

Neonatal alloimmune thrombocytopaenia associated with maternal HLA antibodies

Neonatal alloimmune thrombocytopaenia (NAIT) generally results from platelet opsonisation by maternal antibodies against fetal platelet antigens inherited from the infant’s father. Newborn monochorionic twins presented with petechial haemorrhages at 10...

Alloimmune Thrombocytopaenic Disorders: A Review

Alloimmune thrombocytopaenia (AIT) is caused by alloantibodies against specific platelet glycoproteins. Alloimmune thrombocytopaenic disorders include alloimmune neonatal thrombocytopaenia, posttransfusion purpura, refractoriness to platelet transfusions, passive AIT, and transplantation-associated AIT. In this review we have summarised five thrombocytopaenic syndromes caused by platelet-reactive alloantibodies. Increased awareness of these syndromes, together with the greater availability of highly specialised laboratory methods to detect and to characterise platelet-reactive alloantibodies, will lead to their more frequent diagnosis.

May–Hegglin anomaly and pregnancy

May-Hegglin anomaly (MHA) is an autosomal dominant disorder, characterized by a variable degree of thrombocytopaenia, large platelets and inclusion bodies in white blood cells. Bleeding manifestations are generally mild, but severe bleeding episodes have been reported. This is a systematic review of literature for MHA during pregnancy. The review revealed 26 articles (25 case reports and one case series) including 75 pregnancies (five twin pregnancies) in 40 women. In 11 women, first presentation was incidental thrombocytopaenia during routine antenatal blood test. Of these, five women were misdiagnosed as idiopathic thrombocytopenic purpura (ITP), including three who underwent splenectomy for resistant ITP. Postpartum haemorrhage (PPH) and bleeding after miscarriage were presenting symptoms in two women. Antiplatelet antibody was found in three pregnancies. Only one of them required intervention with intravenous immunoglobulin (IVIG) to prevent neonatal alloimmune thrombocytopaenia. PPH was reported in four pregnancies; three were primary PPH, of which one had blood transfusion, one had platelet and cryoprecipitate transfusion and the third was managed conservatively. There was one secondary PPH that was treated conservatively. Neonatal outcome included 78 live neonates and two intrauterine fetal deaths. Thirty-four neonates had thrombocytopaenia and subsequently were diagnosed with MHA, three of them required platelet transfusion prophylactically as they developed very low platelet counts and one neonate with platelet count of 29 × 10 cells/l and received IVIG, as the mother had a positive antiplatelet antibody during pregnancy. No obvious bleeding complications were reported among the neonates. MHA can present challenges during pregnancy and be associated with adverse maternal and neonatal outcome because of bleeding complications. Joint management by obstetrician and haematologists is required to minimize these risks.

Prevalence of the HPA‐18w to ‐21w alleles in the Chinese Han population

Recently, four new platelet alloantigen (HPA) systems HPA-18w to-21w were identified. However, genotyping for HPA-18w to -21w alleles was rarely reported. Here, we established a polymerase chain reaction sequence-based typing (PCR-SBT) method and investigated the distribution of HPA-18w to -21w alleles in the Chinese Han population. The specific primers of HPA-18w, -19w, -20w and -21w were designed, and the PCR products were bidirectionally sequenced. 855 randomly selected platelet donors were genotyped for HPA-18w to -21w with the PCR-SBT method. The results showed that all individuals were monomorphic for HPA-18w to HPA-20w with a/a homozygous frequency of 1.0 and absence of HPA-18bw to -20bw alleles. The frequencies of the HPA-21a/21a and HPA-21a/21b genotypes were 0.981(839/855) and 0.019(16/855), respectively. Seven mutations were confirmed on sequenced region separate from HPA polymorphisms, including ITGA2 (IVS17+48G>A and IVS17+72G>A), ITGA2B (IVS19-26C>G) and ITGB3 (IVS4+234C>T, IVS11-19 T>C, IVS11-104T>C and GT repeats from IVS11-131 to IVS11-109). These data will provide useful information for diagnosis, prevention and treatment of alloimmune thrombocytopaenia.

Fetomaternal alloimmunity as a cause of liver disease.

Fetomaternal alloimmune disease has traditionally been associated with haematological disease such as fetomaternal alloimmune thrombocytopaenia and Rh haemolytic anaemia, but is now known to also be organ specific. Alloimmune membranous glomerulonephritis (AMG) is one of the most well understood organ-specific alloimmune diseases. Neonatal haemochromatosis (NH) is a rare condition characterised by early liver failure in infants, with evidence suggesting that it is also alloimmune. Both AMG and NH appear to involve the passive transfer of alloantibodies to the fetus, which bind a specific alloantigen, fix complement and activate the terminal complement cascade. Although differences between AMG and NH are known, and evidence of the presence of antigen-specific alloantibodies in NH is still missing, we will use AMG as an example of fetomaternal organ specific alloimmune disease, and critically compare this to other emerging evidence that indicates that NH is also alloimmune.

A tertiary unit experience of utilising immunoglobulin to prevent fetal-neonatal allo-immune thrombocytopaenia

IntroductionFetal-neonatal allo-immune thrombocytopaenia (FNAIT) is associated with significant risks (up to 79%) of intracranial bleeding. Maternal immunoglobulin is a relatively new method of preventing recurrence in a subsequent pregnancy.MethodCase notes...

Severe neonatal alloimmune thrombocytopaenia with anaemia

Severe neonatal alloimmune thrombocytopaenia with anaemia

Allo-immune Thrombocytopaenia

This case report describes the prenatal diagnosis of an intracranial haemorrhage due to allo-immune thrombocytopaenia (AITP) with HPA-1b incompatibility. In this family, a previous child had died neonatally with a presumed diagnosis of schizencephaly. Severe open-lip schizencephaly can be difficult to differentiate from destructive brain lesions due to intracranial haemorrhage, but a correct diagnosis is important due to the high recurrence risk and more severe manifestations in subsequent pregnancies with AITP.

Foetal and neonatal alloimmune thrombocytopaenia.

Foetal/neonatal alloimmune thrombocytopaenia (NAIT) results from maternal alloimmunisation against foetal platelet antigens inherited from the father and different from those present in the mother, and usually presents as a severe isolated thrombocytopaenia in otherwise healthy newborns. The incidence has been estimated at 1/800 to 1/1 000 live births. NAIT has been considered to be the platelet counterpart of Rh Haemolytic Disease of the Newborn (RHD). Unlike RHD, NAIT can occur during a first pregnancy. The spectrum of the disease may range from sub-clinical moderate thrombocytopaenia to life-threatening bleeding in the neonatal period. Mildly affected infants may be asymptomatic. In those with severe thrombocytopaenia, the most common presentations are petechiae, purpura or cephalohaematoma at birth, associated with major risk of intracranial haemorrhage (up to 20% of reported cases), which leads to death or neurological sequelae. Alloimmune thrombocytopaenia is more often unexpected and is usually diagnosed after birth. Once suspected, the diagnosis is confirmed by demonstration of maternal antiplatelet alloantibodies directed against a paternal antigen inherited by the foetus/neonate. Post-natal management involves transfusion of platelets devoid of this antigen, and should not be delayed by biological confirmation of the diagnosis (once the diagnosis is suspected), especially in case of severe thrombocytopaenia. Prompt diagnosis and treatment are essential to reduce the chances of death and disability due to haemorrhage. Due to the high rate of recurrence and increased severity of the foetal thrombocytopaenia in successive pregnancies, antenatal therapy should be offered. However, management of high-risk pregnancies is still a matter of discussion.