True risk of fetal/neonatal alloimmune thrombocytopenia in subsequent pregnancies: a prospective observational follow-up study.

OBJECTIVES: To assess neonatal platelet counts by comparing alloimmunised pregnancies from a Norwegian screening and intervention study with subsequent pregnancies from the same women. DESIGN: Prospective observational follow-up study. SETTING: A university hospital. POPULATION: HPA-1a immunised women from a large Norwegian screening study that gave birth to one or more children after the screening study ended (2004-2012). METHODS: Follow-up of maternal anti-HPA-1a antibody levels and neonatal platelet counts from the screening pregnancies were compared with subsequent pregnancies. None of the women received antenatal intravenous immunoglobulin (IVIG) treatment and neonatal platelet counts were therefore comparable. MAIN OUTCOME MEASURES: Change in neonatal platelet counts from one HPA-1a incompatible pregnancy to the next. Maternal anti-HPA-a1 antibody levels from one HPA-1a incompatible pregnancy to the next. RESULTS: Forty-five incompatible subsequent pregnancies were identified. Overall, the neonatal platelet count in the subsequent pregnancy was improved (18%), unchanged (52%), or worse (30%), compared with the corresponding screening pregnancy. There was one case of fetal intracranial haemorrhage (ICH) identified in the screening (intrauterine fetal death detected at 30 weeks of gestation) and no ICH cases recorded for the subsequent pregnancies. In cases where the platelet count was lower in the subsequent pregnancy, the maternal anti-HPA-1a antibody level was higher compared with the screening pregnancy. In comparison, the maternal antibody level was lower in subsequent pregnancies where the platelet count improved. CONCLUSIONS: In contrast to what is often stated, we found that the neonatal platelet count was increased or unchanged in the majority of subsequent pregnancies of HPA-1a-immunised women.

Maternal anti-HLA class I antibodies are associated with reduced birth weight in thrombocytopenic neonates.

In this comparative cross-sectional study, possible associations between maternal anti-HLA class I antibodies and birth weight in neonatal thrombocytopenia are explored. Although commonly detected in pregnancies and generally regarded as harmless, it has been suggested that such antibodies might be associated with fetal and neonatal alloimmune thrombocytopenia (FNAIT). As a link between FNAIT due to human platelet antigen 1a-specific antibodies and reduced birth weight in boys has previously been demonstrated, we wanted to explore whether maternal anti-HLA class I antibodies might also affect birth weight. To examine this, suspected cases of FNAIT referred to the Norwegian National Unit for Platelet Immunology during the period 1998-2009 were identified. Pregnancies where the only finding was maternal anti-HLA class I antibodies were included. An unselected group of pregnant women participating in a prospective study investigating maternal-fetal hemodynamics at the University Hospital North Norway during the years 2006-2010 served as controls. Twenty-nine percent of controls had anti-HLA class I antibodies. The thrombocytopenic neonates had a significantly lower adjusted birth weight (linear regression, P=0.036) and significantly higher odds of being small for gestational age (OR=6.72, P<0.001) compared with controls. Increasing anti-HLA class I antibody levels in the mother were significantly associated with lower birth weight and placental weight among thrombocytopenic neonates, but not among controls. These results indicate that maternal anti-HLA class I antibodies in thrombocytopenic neonates are associated with reduced fetal growth. Further studies are needed to test if placental function is affected.

Stochastic model for estimating the risk of transfusion-transmitted hepatitis B in Vietnam.

BACKGROUND AND OBJECTIVE: Transfusion-transmitted hepatitis B virus (HBV) infection may originate from hepatitis B surface antigen (HBsAg) false-negative blood donors, HBsAg negative and anti-HBc positive blood donors and blood donors with both tests negative. HBV DNA may be present in all these cases and blood may be infectious. The aim of the study was to estimate the risk of transfusion-transmitted HBV in Vietnam using a stochastic Monte Carlo model. METHODS: A cross-sectional study of HBV prevalence in 1200 potential blood donors in rural Vietnam is used as basis for the Monte Carlo model together with expert panel estimates of occult hepatitis B infection (OBI) prevalence in blood donors. RESULTS: With 1 000 000 blood donors running in the model, the potential OBI ranged from 658 to 747 blood units per million at 5 percentile and from 1342 to 2507 blood units per million at 95 percentile resulting in the risk of post-transfusion hepatitis ranging from 66 to 250 blood units per million assuming that risk of post-transfusion from potential OBI is 10%. Using the manufacturer's HBsAg sensitivity, the mean rate of blood units per million donations having false-negative HBsAg results was 298 (5-95 percentile: 14-893). When the test sensitivity was set lower, false-negative tests was observed at a mean of 1087 per million (5-95 percentile: 762-3220). The fraction of potential OBI donors increased with the increasing age in both genders. CONCLUSION: Current HBsAg screening in Vietnam is insufficient in eliminating the risk of transfusion-transmitted HBV infection. The major risk factors are HBsAg false-negative results and OBI. Increased test sensitivity and locally validated HBsAg assays are recommended.

Foetal/neonatal alloimmune thrombocytopenia in Egypt; human platelet antigen genotype frequencies and antibody detection and follow-up in pregnancies.

BACKGROUND AND OBJECTIVES: Foetal and neonatal alloimmune thrombocytopenia (FNAIT) is studied mainly in Caucasian populations. Severe thrombocytopenia (<50×10(9)/L) gives risk of haemorrhage and the most feared complication is intracranial haemorrhage (ICH). In Caucasian populations anti-human platelet antigen (HPA)-1a antibodies are the cause of FNAIT in >80% of the cases. The aims of this project were to study the gene frequencies of HPA-1-5 and 15 alleles in an Egyptian population (Arabic), and to determine the frequency of HPA-1a and -5b immunisations in a cohort of Egyptian pregnant women. MATERIALS AND METHODS: Altogether 6974 pregnant women were included in the study. Genotyping was performed by polymerase chain reaction and antibodies were detected by flow cytometry and enzyme-linked immunosorbent assay. HPA-1-5 and 15 alleles were studied in 367 individuals. RESULTS: The HPA genotypes differed from genotypes published from different Caucasian and Chinese (Han) populations in HPA-1, -2, -3, and -5 systems with significant higher frequency of HPA-1b, -2b and -5b. The rate of HPA-1a alloimmunisation was found comparable to Caucasian populations. Severe thrombocytopenia was found in two newborns. No bleeding complication was reported. Anti-HPA-5b antibodies were detected in 4.4% of the pregnant women. Clinical consequences of these antibodies were not studied. CONCLUSION: The HPA-1bb and -5bb genotypes are more frequent in the Egyptian Arabic population studied compared to Caucasian populations. FNAIT due to anti-HPA-1a and -5b antibodies must be suspected in cases of neonatal thrombocytopenia. Further large prospective studies are needed to increase the knowledge of clinical complications related to HPA alloantibodies in populations with different genetic backgrounds.

IFPA Meeting 2011 workshop report III: Placental immunology; epigenetic and microRNA-dependent gene regulation; comparative placentation; trophoblast differentiation; stem cells.

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialised topics. At IFPA meeting 2011 there were twelve themed workshops, five of which are summarized in this report. These workshops related to various aspects of placental biology: 1) immunology; 2) epigenetics; 3) comparative placentation; 4) trophoblast differentiation; 5) stem cells.

Neonatal alloimmune thrombocytopenia is not what it was: a lesson learned from a large prospective screening and intervention program.

Controversies regarding the pathophysiology of neonatal alloimmune thrombocytopenia (NAIT) has hampered the development of consensus about how to identify, follow up and treat the women and children with this serious complication. One reason for this is that knowledge about the condition derived from previous retrospective studies do not necessarily conform with data derived from prospective investigations. The main obstacle to introduction of general screening programs to identify the pregnancies to treat, have been lack of reliable risk factors, and an effective treatment. Now, several recent prospective screening programs including up to 100,000 pregnant women has changed the understanding of the NAIT-pathology, and has shown that we are close to answering these critical questions.

Neonatal alloimmune thrombocytopenia in Norway: poor detection rate with nonscreening versus a general screening programme.

The implementation of an antenatal screening programme for neonatal alloimmune thrombocytopenia (NAIT) is currently under debate. We evaluated the detection rate for NAIT in a nonscreened population of 661,200 births where NAIT was diagnosed on clinical indication. We did a cross-sectional comparison with a population of 100,448 human platelet antigen 1a (HPA1a)-screened pregnancies from three of the five health regions in Norway. In a nonscreening situation, 7.5 cases of NAIT were detected per year compared with 53 cases when screening was applied. The detection rate of NAIT in Norway was therefore 14% of the expected rate.

What's happening--probing of HPA-1a antigen-antibody interaction by surface plasmon resonance technology.

This brief report summarizes the use of surface plasmon resonance technology (SPRT) in probing HPA-1a antigen-antibody interactions, based on a poster presented at the 60th meeting of the American Association of Blood Banks. It was concluded that the GP purification method could affect the performance of antigen in SPRT. It also highlighted that chips immobilised with Monoclonal antibody (Mab)-purified GP-IIb/IIIa work satisfactorily with both monoclonal and recombinant Abs with the appropriate concentration and binding affinity, while determination of the avidity and concentration of maternal polyclonal antibodies in respect to clinical severity on NAIT warrants further development.

Severe antibody-mediated agranulocytosis.

A 56-year-old female with Crohn's disease was admitted to the hospital with malaise, fever, and a low white blood cell count (0.8 x 10(9)/l) with no granulocytes or myeloid precursor cells in the bone marrow. The leucopenia was initially thought to be the result of an infection and she was treated with antibiotics and granulocyte colony-stimulating factor (G-CSF, filgrastim). However, the bacterial cultures and viral tests were all negative. The patient's condition deteriorated and she became morbidly ill, but recovered after high dose steroid treatment. Six weeks later she relapsed whilst receiving 7.5 mg daily dose of prednisolone. She recovered quickly after being given high dose methylprednisolone in combination with filgrastim. A high maintenance dose of prednisolone was tapered over 5 months. She has not relapsed since and is currently well. Antibodies to the human neutrophil antigen (HNA)-3a were detected, but these antibodies could not easily explain her agranulocytosis as she had a HNA-3a negative phenotype. It seems plausible that her agranulocytosis was immune mediated through autoantibodies directed towards the early myeloid cells.

Alterations in antral cytokine gene expression in peptic ulcer patients during ulcer healing and after Helicobacter pylori eradication.

Earlier studies have shown that the antral immune response in Helicobacter pylori infection has a mixed Th1-Th2-T-regulatory profile. After eradication, a chronic inflammation remains in some patients, but a follow-up study with a comprehensive cytokine profile in has not previously been published. Twelve patients with H. pylori positive peptic ulcer disease (five antral and seven duodenal) were enrolled and cytokine gene expressions in antral biopsies were determined (1) at entry, (2) after resolving the ulcer with proton pump inhibitor (PPI) treatment and (3) after eradication. The second endoscopy was performed 4 weeks after ending the PPI treatment, and the third endoscopy was performed after a mean of 10 months after eradication. Inflammation was graded according to the updated Sydney system. Interleukin (IL)1beta, IL8, IL12A, IL18, TNFalpha, IFNgamma, IL4, IL6 and IL10 expression levels were analysed by real-time RT-PCR. Mixed mononuclear and neutrophil infiltrates were seen at entry and after ulcer healing. After eradication, low-grade mononuclear infiltrates were found. The cytokine expression levels after ulcer healing (H. pylori positive gastritis) were not significantly different from the levels at entry (ulcer). After eradication, attenuation of the Th1 cytokines except for TNFalpha and a persisting increase of IL4 levels were observed, whereas the IL10 expression was markedly reduced. The present data did not indicate a specific ulcer promoting cytokine gene regulation profile. However, after eradication a chronic low-grade inflammation was seen with reduced Th1, prolonged Th2 and disappearance of the T-regulatory response.

Monoclonal platelet antigen capture assays (MAIPA) and reagents: a statement.

This statement concerning the monoclonal-specific immobilization of platelet antigens (MAIPA) has been written on behalf of the International Society of Blood Transfusion--Working Party on Platelet Immunology. The MAIPA technique is considered as the gold standard reference technique in platelet immunology. The assay performed with reagents labelled for 'research only' is acceptable as long as it is regularly evaluated by participation of laboratories in national or international workshops held with reference laboratories.

Cost-effectiveness of antenatal screening for neonatal alloimmune thrombocytopenia.

OBJECTIVES: To estimate the costs and health consequences of three different screening strategies for neonatal alloimmune thrombocytopenia (NAIT). DESIGN: Cost-utility analysis on the basis of a decision tree that incorporates the relevant strategies and outcomes. SETTING: Three health regions in Norway encompassing a 2.78 million population. POPULATION: Pregnant women (n = 100,448) screened for human platelet antigen (HPA) 1a and anti-HPA 1a antibodies, and their babies. METHOD: Decision tree analysis. In three branches of the decision tree, pregnant women entered a programme while in one no screening was performed. The three different screening strategies included all HPA 1a negative women, only HPA 1a negative, HLA DRB3*0101 positive women or only HPA 1a negative women with high level of anti-HPA 1a antibodies. Included women underwent ultrasound examination and elective caesarean section 2-4 weeks before term. Severely thrombocytopenic newborn were transfused immediately with compatible platelets. MAIN OUTCOME MEASUREMENTS: Quality-adjusted life years (QALYs) and costs. RESULTS: Compared with no screening, a programme of screening and subsequent treatment would generate between 210 and 230 additional QALYs among 100,000 pregnant women, and at the same time, reduce health care costs by approximately 1.7 million euros. The sensitivity analyses indicate that screening is cost effective or even cost saving within a wide range of probabilities and costs. CONCLUSION: Our calculations indicate that it is possible to establish an antenatal screening programme for NAIT that is cost effective.

Increased frequency of antral CD4 T and CD19 B cells in patients with Helicobacter pylori-related peptic ulcer disease.

Only a fraction of Helicobacter pylori (HP)-infected individuals develop clinical disease. Recent research indicates that immunological mechanisms may be important for understanding the pathophysiology of HP infection. Differences in the individual cellular immune response may reflect the clinical diversity. The aim of the present study was to investigate the cellular immune response against HP in three clinically well-defined patient groups: HP-positive peptic ulcer, HP-positive and HP-negative gastritis. Biopsies from gastric mucosa were processed for analysis by flow cytometry and histology. The number of T lymphocytes (CD3+) was significantly higher in HP-positive peptic ulcer (13.8%) than in HP-positive nonulcer gastritis (6.3%). A nonsignificant increase for B lymphocytes (CD19+) was noted as well. Furthermore, a significant difference was seen in mucosal CD4/CD8 ratio between HP ulcer (2.4) and nonulcer HP gastritis (1.0) patients. Thus, B cells (CD19+) and T-helper cells (CD4+) were dominant in gastric mucosa from peptic ulcer patients, and cytotoxic T cells (CD8+) were relatively dominant in gastric mucosa from nonulcer patients. In conclusion, distinct differences in the T-cell subset distribution of mucosal lymphocytes were detected in patients with HP infection, strongly correlated with the presence or absence of peptic ulcer.

Humoral immunity to viral and bacterial antigens in lymphoma patients 4-10 years after high-dose therapy with ABMT. Serological responses to revaccinations according to EBMT guidelines.

The aim of this study was to investigate the late effects of ABMT on the immune system with regard to protective humoral immunity against common antigens and responses to recall antigens (vaccines). The vaccines were given according to EBMT guidelines from 1995. The protocol included 35 patients with malignant lymphoma in CR 4-10 years after ABMT, and 35 controls. The results show that prior to ABMT the proportion of patients with protective immunity against poliomyelitis, tetanus and diphtheria was similar to that of controls. At study entry 4-10 years after ABMT, the proportion of patients with protective immunity against poliomyelitis and diphtheria was reduced, while all patients maintained protection against tetanus. A significant decrease in geometric mean antibody concentrations or titres was observed against all three antigens during this period. Serum levels of antibodies against different pneumococcal serotypes were lower in the patients than in the controls prior to vaccination. The responses to pneumococcal vaccination, which is considered to be a T cell-independent vaccine, were studied. Unlike controls, a minority of patients achieved protective levels of antibodies after a single vaccination. Despite persistent levels of protective antibodies in many patients post ABMT, secondary booster responses after one vaccination with T cell-dependent vaccines (tetanus, diphtheria and polio) were absent. In conclusion, this study shows that post ABMT, a full re-vaccination program was necessary to mount responses comparable to those observed after a single vaccination in controls.

Radioimmunotherapy with iodine-131 tositumomab in patients with low-grade non-Hodgkin's B-cell lymphoma does not induce loss of acquired humoral immunity against common antigens.

Thirty-one previously untreated patients with follicular low-grade B-cell non-Hodgkin's lymphoma expressing the CD20 antigen were treated with iodine-131 tositumomab therapy between 1996 and 1998. The therapy led to a temporary depletion of peripheral blood B-lymphocytes. Recovery of B-cells occurred in most cases by 3 to 6 months and in all patients by 12 months posttherapy. A temporary decline in T-cell subpopulations, but no reduction in serum immunoglobulin levels, could be observed. ELISA techniques were used to detect specific antibodies against rubella, mumps, varicella zoster, measles, and tetanus. Almost all patients remained seropositive against the different antigens during the 1- to 2-year follow-up. No significant reduction in antibody concentrations to tetanus or measles could be detected. The data show that acquired humoral immunity against common antigens appears to be preserved despite a temporary loss of B-lymphocytes.

[Significance of maternal alloantibodies for neonatal thrombocytopenia]. / Maternelle alloantistoffers betydning ved trombocytopeni hos nyfødte.

BACKGROUND: Thrombocytopenia has been shown to be present in about 1% of unselected newborns. Alloantibodies to platelets induce the most severe thrombocytopenia. MATERIAL AND METHODS: Samples from 195 mothers who had just given birth to thrombocytopenic children, were analysed by platelet antigen genotyping and detection of platelet specific antibodies. RESULTS: 75 mothers were typed human platelet antigen (HPA) 1bb, and in 65 mother, anti-HPA 1a antibodies could be detected. Anti-HPA 5b antibodies were detected in three samples and anti-HLA antibodies in 73 samples. INTERPRETATION: Alloantibodies were shown to be an important cause of thrombocytopenia in the new-born children and anti-HPA 1a antibodies were, as expected, the most common platelet-specific antibody involved. Anti-HLA class 1 antibodies were detected as the only antibody in 51 cases of thrombocytopenia. Though it is not yet formally shown, this may indicate that anti-HLA class 1 antibodies may cause thrombocytopenia in the fetus and new-born. Based on the assumption that neonatal alloimmune thrombocytopenia is present in 1:1,000 new-born, 25% of the neonatal alloimmune thrombocytopenia cases in Norway are verified by laboratory analysis. Alloantibodies to thrombocytes are of clinical importance in future pregnancies and transfusions. The cost and benefit of a national screening program for anti-HPA 1a antibodies in all pregnant women should be carefully considered.

Neonatal alloimmune thrombocytopenia due to anti-HPA 1a antibodies; the level of maternal antibodies predicts the severity of thrombocytopenia in the newborn.

Eleven thousand one hundred pregnant women were genotyped for human platelet antigen HPA 1, and 198 HPA 1bb women were followed in the pregnancy with quantitative assay for anti-HPA la antibodies. Antibodies were detected in 24 women, and nine children were born with severe thrombocytopenia (< 50x10(9)/L). All mothers with high levels of antibodies were delivered of children with severe thrombocytopenia. None of the newborn infants had clinical signs of intra-cranial haemorrhage. The level of maternal anti-HPA 1a antibodies is predictive for fetal thrombocytopenia and may be used in decisions related to time and mode of delivery.