Serological and clinical aspects of granulocyte antibodies leading to alloimmune neonatal neutropenia

Eighteen cases of alloimmune neonatal neutropenia (ANN) were analysed for their clinical and serological properties. Pregnancy was normal in all cases, but a 50% incidence of abortion is recorded. With the exception of two premature babies, all newborns were delivered at term. Omphalitis and mild infections of the skin were predominantly present. None of the new-borns died by overwhelming sepsis. The average duration of neutropenia was 11 weeks (range 3-28 weeks). Intravenous IgG therapy was followed by transient remission in 2 of 4 affected newborns. Antibody differentiation revealed in five sera NA1-, in four sera NA2- and in two sera NB1-specific antibodies. In two sera only HLA antibodies were detectable. Complement activating antibodies were determined in 72% of the sera. Screening for granulocyte-specific antibodies in 1016 postpartum sera of unselected women revealed a total of 11 sera (1.1%) reacting selectively with granulocytes, but only four (0.4%) were directed against a known granulocyte-specific antigen. None of the new-born of mothers alloimmunized to granulocyte antigens developed neutropenia, which suggests an incidence of ANN below 0.1%.     

A possible role for maternal HLA antibody in a case of alloimmune neonatal neutropenia

BACKGROUND: Alloimmune neonatal neutropenia (ANN) is caused by a reaction of maternal alloantibodies with paternally inherited antigens on the fetal neutrophils. While human neutrophil antigens (HNA) antibodies are found in half of ANN cases, specific antibodies have not been defined in the remaining cases. STUDY DESIGN AND METHODS: Reported here is a neonate with omphalitis due to neutropenia. To elucidate the cause of ANN, flow cytometric and PCR analyses were used. Reactions of the patient's and mother's sera with neutrophils, lymphocytes, and platelets were examined by lymphocytotoxicity test (LCT), anti-human immunoglobulin-LCT, and mixed passive hemagglutination test. RESULTS: The maternal sera reacted with neutrophils, lymphocytes, and platelets of the patient and father. The platelet adsorption eliminated the reaction of the maternal serum with the patient's neutrophils. The HLA typing of the family and an LCT using a panel of lymphocytes of 20 HLA-typed donors showed HLA-A2 antigen as a target of antibodies in the maternal serum. According to anti-human immunoglobulin-LCT, the anti-HLA-A2 was present in the neonatal serum. On the other hand, HNA antibodies were not detectable in the patient's or the mother's serum. CONCLUSION: These results suggest that the transplacental passage of the maternal HLA antibody caused neutropenia in this patient.     

Isoimmune neonatal neutropenia due to anti-Fc(gamma) RIIIb antibody in a mother with an Fc(gamma) RIIIb deficiency

A rare case of neutropenia in a newborn due to anti-Fc(gamma) RIIIb antibody is described. The newborn, born from the 5th pregnancy, had severe infection and no neutrophils. Full clinical and neutrophil count recovery was observed when the child was 5 weeks old. In maternal serum, panreactive granulocyte alloantibodies were detected. The mother's and her two sisters' granulocytes appeared to be Fc(gamma) RIIIb deficient as found using pheno- and genotyping methods. All of them were healthy. The anti-Fc(gamma) RIIIb specificity of antibodies was identified by the monoclonal antibody immunobilization of neutrophil antigen assay. Such antibodies were not found in both sisters with the Fc(gamma) RIIIb deficiency, although they were pregnant, one of them on the seventh occasion.     

Implication of antibodies against human leukocyte antigen in simultaneous presentation of fetal and neonatal alloimmune thrombocytopenia and neutropenia

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) and neonatal alloimmune neutropenia (NAN) are two rare complications of newborns caused by antibodies against paternal inherited antigens. Human platelet (HPA) and neutrophil antigens (HNA) are the common targets. Human leukocyte antigen (HLA) class I proteins are also expressed on platelets and neutrophils and anti-HLA antibodies have occasionally been implicated in these complications. We report a premature twin infant who presented with severe thrombocytopenia and neutropenia clinically compatible with FNAIT and NAN, from a mother with no identifiable HPA or HNA antibodies, but with very high levels of complement-fixing antibodies against paternal inherited HLA. These antibodies were also detected in the infant. HLA antibodies are commonly present in multiparous women who deliver healthy infants. They can, however, be cytotoxic and cause clinical complications after blood products transfusion (TRALI and becoming refractory to platelets transfusion) and after organ transplantation (allogeneic organ rejection).     

Neonatal alloimmune thrombocytopenia due to an antibody against a labile component of human platelet antigen-3b (Bak b)

We report the second case of neonatal alloimmune thrombocytopenia due to anti-human platelet antigen (HPA)-3b (Bak(b)) antibody. The infant was severely affected with intracranial haemorrhage. Most importantly, we were able to detect this antibody only by using fresh, unfixed platelets as antigen. This antibody was detectable neither by conventional mixed passive haemagglutination, platelet immunofluorescence test using fixed platelets, nor by monoclonal antigen immobilization of platelet antigen assay using solubilized platelets. We assume that this antibody reacts only with fresh platelets and that the antigen is a labile component of HPA-3b (Bak(b)).     

The granulocytes in neutropenia 1 (GIN 1) study: a safety study of granulocytes collected from whole blood and stored in additive solution and plasma

Objective/Aim: To evaluate the safety of transfusing pooled, whole blood‐derived granulocytes in additive solution and plasma (GASP) in 30 recipients. Background: Demand for granulocytes in England has increased five‐fold. With the advantages of reduced red cell, plasma and overall volume, GASP maintains function in vitro. Methods and Materials: Observations were recorded prior to and post transfusion. Increments were recorded at 1 h and the following morning. Leucocyte antibody screening was undertaken prior to and at 1–6 months following transfusion. Results: Thirty patients aged between 8 months and 68 years received 221 GASP in 148 transfusion episodes. GASP contained an average of 1·0 ×10¹⁰ granulocytes in 207 mL. Adults usually received two packs and children 10–20 mL kg^–1. Children and adults received a median [interquartile range (IQR)] dose of 12·5 (9·1–25·3) and 19·7 (12·0–25·8) ×10⁹ granulocytes per transfusion, respectively. There was one episode of transfusion‐associated circulatory overload (TACO) in a patient with chronic cardiac failure following 600 mL of unpooled granulocytes, other fluids and one GASP. New l eucocyte alloimmunisation occurred in 3/30 recipients 10%. No other significant reactions were reported. Median peripheral blood neutrophil increments at 1 h post transfusion were 0·06 (IQR, 0·01–0·17) in children and (0·03) (IQR, 0–0·16) in adults. Conclusion: GASP has a similar safety profile to other sources of granulocytes for patients with refractory infection or in need of secondary prophylactic transfusion. Further studies are required to clarify the role of GASP in the treatment of neutropenic patients.     

The use of genotyping to predict the phenotypes of human platelet antigens 1 through 5 and of neutrophil antigens in Taiwan

BACKGROUND: The human platelet antigen (HPA) 1 through 5 and the human neutrophil antigen (HNA-1) systems are relevant to immune-related thrombocytopenia and neutropenia. The alloantigen distribution profiles in the population will aid in estimating the risk of alloimmunization. STUDY DESIGN AND METHODS: Genotyping of the genes that control the expression of the HPA-1 through -5 and HNA-1 systems in Taiwanese (n = 326) and Taiwan's indigenous peoples (n = 608) was performed by PCR with the sequence-specific primer (PCR-SSP) method. RESULTS: In the HPA system, HPA-1b and HPA-4b were absent among Taiwan's indigenous tribes and detected among other Taiwanese only with frequencies of <0.2 percent and <0.5 percent, respectively. The GP1BA*2 (HPA-2b) and GP1A*2 (HPA-5b) allele frequencies range from 1 percent to 7 percent and 0.4 percent to 3.5 percent among the two ethnic groups, respectively. GP2B*1 (HPA-3a) and GP2B*2 (HPA-3b) showed similar allele frequencies. In the HNA-1 system, the FCGR3B*1 (HNA-1a) allele frequency was about twice that of FCGR3B*2 (HNA-1b) in Taiwanese and also in most of the indigenous tribes. Three FCGR3B (HNA-1) null persons were found in one indigenous tribe (Ami tribe), for an FCGR3B null frequency of 19.8 percent. However, no FCGR3B*3 (HNA-1c) allele was detected in Taiwan. CONCLUSION: The frequencies of HPA-1b, -2b, and -5b in the Taiwanese population were much lower than those among whites. In Taiwan, all of the HNA-1 null found was due to the deletion of the FCGR3B gene, and this deletion may be widely distributed in the Ami tribe.     

Neutrophil antigen 5b is carried by a protein, migrating from 70 to 95 kDa, and may be involved in neonatal alloimmune neutropenia

BACKGROUND: Neutrophil antigen 5b has been described as involved in transfusion reactions and not in neonatal alloimmune neutropenia. CASE REPORT: Anti-5b was found in the serum of a mother of a persistently neutropenic newborn, who had several bacterial infections. The neutropenia responded to treatment with recombinant human granulocyte-colony-stimulating factor. Immunoprecipitation experiments performed with this and three other 5b antisera identified a protein, migrating from 70 to 95 kDa, as carrier of 5b. The observed pattern of migration may point to heavy glycosylation of this protein. RESULTS: Six 5b-negative donors were identified among 54 screened white donors, for a 5b gene frequency of 0.66. CONCLUSION: Alloimmunization to 5b in pregnancy is rare. In the patients with neonatal neutropenia analyzed in the last decade, this was the first case discovered.