Neonatal neutropenia and bacterial sepsis associated with placental transfer of maternal neutrophil-specific autoantibodies.

BACKGROUND: Passively acquired neonatal neutropenia is an infrequently reported complication of maternal autoimmune neutropenia (AIN). Two affected siblings are described. The firstborn developed Citrobacter meningitis and was permanently disabled. The second was success-fully managed with pre- and postnatal injections of recombinant human granulocyte colony-stimulating factor (rHuG-CSF). STUDY DESIGN AND METHODS: Neutrophil-specific antibodies were evaluated by flow cytometry (FC), monoclonal antibody immobilization of granulocyte antigens, and granulocyte agglutination assays. RESULTS: A neutrophil-reactive antibody was detected by FC in samples of the mother's serum spanning a 4-year time frame. This antibody reacted with neutrophils from the mother, father, and their first infant and with 18 of 20 target neutrophils tested. In serologic studies, it was shown that the antibody was not specific for the commonly recognized neutrophil-specific alloantigens HNA-1a (NA1), HNA-1b (NA2), HNA-1c (SH), HNA-2a (NB1), or HNA-3a (5b). CONCLUSION: Severe neonatal neutropenia in the two siblings appears to have been caused by placental transfer of a maternal neutrophil-reactive autoantibody of undetermined specificity. Neutrophil counts should be evaluated in infants born to mothers with chronic neutropenia of possible autoimmune origin so that neutropenic infants can be carefully monitored and antibiotics and/or rHuG-CSF administered if indicated.

Human platelet antigen-specific alloantibodies implicated in 1162 cases of neonatal alloimmune thrombocytopenia.

BACKGROUND: Neonatal alloimmune thrombocytopenia (NATP) caused by fetomaternal mismatch for human platelet (PLT) alloantigens (HPAs) complicates approximately 1 in 1000 to 1 in 2000 pregnancies and can lead to a serious bleeding diathesis, intracranial hemorrhage, and sometimes death of the fetus or neonate. As a national reference center for NATP investigations, our experience with this entity over a 12-year period was reviewed. STUDY DESIGN AND METHODS: The laboratory records of all cases of suspected NATP referred for evaluation from January 1, 1990, to December 31, 2002, were analyzed. The spectrum of PLT alloantibody specificities identified was compared with an earlier reported series of serologically verified NATP cases. RESULTS: HPA-specific alloantibodies were identified in 1162 (31%) of 3743 sera of mothers of infants with clinically suspected NATP. Maternal HPA-1a (PlA1) alloimmunization accounted for the majority (79%) of confirmed NATP cases, with HPA-5b (Bra), HPA-3a (Baka), and HPA-1b (PLA2) alloantibodies accounting for 9, 2, and 4 percent of cases, respectively. In addition, an increase in the number of cases in which multiple HPA-specific alloantibodies were present in maternal sera was observed during the study period. CONCLUSION: Although, as with the earlier series, maternal HPA-1a alloimmunization was the dominant cause of NATP, the identification of an increasing number of cases due to alternative HPA polymorphisms suggests that investigation for HPA-1 incompatibility alone is no longer sufficient to fully evaluate clinically suspect NATP cases.

Ex vivo cytokine responses against parvovirus B19 antigens in previously infected pregnant women.

Parvovirus B19 infection is a significant cause of fetal death. The aim of this study was to investigate the role of maternal immune status in modulating susceptibility to fetal B19 infection. Peripheral blood was obtained from pregnant women (n = 199) with no clinical evidence of recent B19 infection. Evaluation of ex vivo T cell responses from 149/199 individuals showed significantly higher interferon-gamma levels for seropositive individuals following VP1 (268 +/- 36 versus 103 +/- 19 pg/ml; P = 0.003) and VP2 (242 +/- 42 versus 91 +/- 16 pg/ml; P = 0.01) antigen stimulation. Significantly higher levels of interleukin-2 were also observed in seropositive individuals following both VP1 (P = 0.0003) and VP2 (P = 0.0005) stimulation. The observed Th1 cellular response is lower than that documented previously for non-pregnant individuals and strongly suggests that diminution of the maternal anti-viral immune response may increase susceptibility to fetal B19 infection.

Antenatal screening for human platelet antigen-1a: results of a prospective study at a large maternity hospital in Ireland.

OBJECTIVE: Fetomaternal mismatch for human platelet antigen (HPA)-1a accounts for approximately 85% of cases of neonatal alloimmune thrombocytopenia. The purpose of the study was to determine the prevalence of the HPA-1a negative platelet phenotype in a cohort of pregnant women in Ireland, the rate of alloimmunisation to HPA-1a in HPA-1 mismatched pregnancies and the associated incidence of neonatal alloimmune thrombocytopenia. DESIGN: A prospective case-control study. SETTING: The antenatal clinics of a large maternity teaching hospital. POPULATION OF SAMPLE: Pregnant women, regardless of parity, presenting at the antenatal clinics. METHODS: An enzyme-linked immunosorbent assay (ELISA) designed for simultaneous HPA-1a typing and antibody detection was used. Further analysis for HPA-1a alloantibodies was performed using commercial ELISA's (GTI PakPlus and Pak1) and the monoclonal antibody immobilisation of platelet antigens assay. Confirmation of serological typing was by the polymerase chain reaction technique using sequence-specific primers (PCR-SSP). MAIN OUTCOME MEASURES: The presence of the HPA-1a negative phenotype and its association with the development of maternal anti-HPA-1a and infant thrombocytopenia. RESULTS: Eighty-four of 4090 consecutive women enrolled in the study tested positive for HPA-1a in the screening ELISA. Confirmatory genotyping was performed on 67 women (representing 80% of the cohort), and 54 women (representing 3272 non-selected pregnancies), were homozygous for the HPA-1b allele (1.7%). Three of 34 (9%) women who delivered HPA-1a positive babies had detectable anti-HPA-1a and all three babies had neonatal alloimmune thrombocytopenia, for an overall incidence of 1:1100 non-selected pregnancies. CONCLUSIONS: The observed prevalence of 1.7% for the HPA-1a negative platelet phenotype is as expected from studies in other countries. While we have demonstrated the practicability of antenatal HPA-1a screening, further research is warranted to investigate maternal parameters predictive of severe fetal thrombocytopenia in HPA-1a alloimmunised pregnancies.

Outcome of an optional HCV screening program for blood transfusion recipients in Ireland.

BACKGROUND: An optional (general) HCV testing program for blood and blood component recipients before the introduction of routine donor anti-HCV screening (October 1991) was launched in Ireland in 1995 to complement the targeted lookback program in progress at that time and to identify transfusion-transmitted hepatitis C. STUDY DESIGN AND METHODS: The public were informed of the opportunity to avail of screening by widespread media coverage. Screening was by an initial ELISA (Abbott 3.0, Abbott Laboratories) at the transfusion center laboratories. Reactive samples were referred to a virus reference laboratory where two additional ELISAs (Ortho 3.0, Ortho Clinical Diagnostics; and Murex 3.0, Murex) were performed. Confirmation of ELISA-positive samples was by a RIBA (RIBA 3.0, Chiron Corp.). All patients found to be anti-HCV- seropositive were tested for HCV RNA by PCR and were referred to a hepatologist. RESULTS: A total of 14,917 persons have been tested for hepatitis C in this program to date (85% women). Sixty-one people were confirmed positive for HCV by RIBA 3.0 (0.4%). Excluding persons with other risk factors (n = 15), the HCV positivity rate for blood component transfusion recipients (n = 46) was 0.3 percent. Of the 46 confirmed hepatitis C-positive blood component transfusion recipients, 32 were women (70%), 24 of whom received transfusion for obstetric or gynecologic indications (75%). Thirty-eight of 46 (83%) anti-HCV seropositive transfusion recipients tested had detectable HCV RNA by PCR. CONCLUSION: This program identified 46 transfusion recipients and 10 coagulation factor concentrate recipients, all of whom were previously unaware of their infection. The majority of HCV-positive transfusion recipients identified were women. This may reflect that women are longer living survivors of transfusion therapy or alternatively, in our experience, that Irish women perceive themselves at greater risk of hepatitis C because of the well-publicized association of this virus with recipients (women) of Irish RhIG.