Granulocyte Antibodies in Korean Neonates with Neutropenia

Neonatal alloimmune neutropenia (NAN) is a disease that can cause severe and prolonged neutropenia in neonates. However, no report is available on the incidence of granulocyte antibody in neonates, the target antigen of this antibody, and the estimated incidence of NAN in Korea. Among a total of 856 neonates admitted to a neonatal intensive care unit (NICU) over a five year period, a total of 105 neonates with neutropenia were enrolled in this study. Positive reactions were observed in the sera of six neonates (5.7%, 6/105) by mixed passive hemagglutination assay (MPHA). To confirm the presence of NAN, MPHA and granulocyte antigen typing (HNA-1a, -1b, -2a, -4a, and -5a) were performed on neonatal and maternal blood. To differentiate granulocyte antibody and HLA antibody, MPHA was also performed using HLA antibody adsorbed serum. We confirmed three cases (2.9%, 3/105) of NAN among neonates with neutropenia in which granulocyte antibody specificities (two anti-HNA-1b and one anti-HNA-1a) and fetomaternal granulocyte antigen mismatches were identified. In this study, the estimated incidence of NAN was 0.35% (3/856) among neonates admitted to NICUs in Korea.

Alloimmunization to Granulocyte Antigens among Korean Pregnant Women / 대한수혈학회지

BACKGROUND: Neonatal alloimmune neutropenia (NAN) is one of the diseases resulting from the transplacental passage of granulocyte antibodies directed against the neonates' neutrophil surface antigens. In order to cause NAN, mothers should be first alloimmunzied against the neutrophil antigens. However, there are no reports on the incidence of granulocyte antibodies in pregnant women or the target antigens of the antibodies in Korea. METHODS: Pregnant women, who visited the outpatient clinic of Obstetrics for antenatal care and had given birth to babies, were enrolled in this study. A total of 650 serum were tested for the granulocyte antibody by a mixed passive hemagglutination assay (MPHA). When an antibody was detected, MPHA was re-performed with the HLA antibody adsorbed serum to differentiate the granulocyte antibody from the HLA antibody. When a granulocyte antibody was confirmed, the patient's granulocyte antigens were typed to support her alloimmnization against the granulocyte antigen. Neutropenia in the neonates, in whose mother's serum granulocyte antibody had been confirmed, was detected by drawing pairs of EDTA and serum samples (n=15) from the neonates between 12 and 24 hours of age. MPHA was then performed using the neonate's serum, and granulocyte antigen typing was typed to confirm NAN. RESULTS: MPHA showed a positive reaction in the sera from 23 women (3.5%, 23/650). Granulocyte antibodies were confirmed in the sera from 15 women (2.3%, 15/650). Among the 15 neonates, whose mothers had granulocyte antibodies in their sera, only two showed neutropenia, and only one had the granulocyte antibody (anti-HNA-1b) in its serum with a fetomaternal granulocyte antigen mismatch. CONCLUSION: In this study, the incidence of granulocyte antibodies in pregnant women was 2.3% (15/650), and the estimated incidence of NAN among live births in Korea was 0.2% (1/650).

Genotype Frequencies of Platelet Glycoprotein IIIa-Specific Antigens and Granulocyte Antigens In Korean Pregnant Women* / 대한수혈학회지

BACKROUND: Polymorphism of glycoprotein IIIa on human platelets is one of the factors in alloimmunization that causes neonatal alloimmune thrombocytopenia (NATP), and the granulocyte antigens NA1 and NA2 are often targets of granulocytes antibodies causing neonatal alloimmune neutropenia (NANP). Currently, serotyping relies on the properties of the typing sera or antibodies and technique used. Genotyping circumvents the problems associated with serotyping. METHODS: The genomic DNA of 200 unrelated pregnant women admitted to Taegu Fatima Hospital was typed for three platelet glycoprotein IIIa-specific antigens (HPA-1, HPA-4, and HPA-6w) and granulocyte antigens (NA1 and NA2). Allele specific amplification test using primer designed to study HPA-1 and HPA-4, restriction fragment length polymorphism to study HPA-6w, and sequence specific primers for NA1 and NA2 were used for genotyping. RESULTS: The genotype frequencies were HPA-1(a+b-) 100%, HPA-4 (a+b-) 97.5%, HPA-4(a+b+) 2.5%, HPA-6w(a+b-) 97%, and HPA-6w(a+b+) 3%. These frequencies are similar to Japanese but different from Caucasian. The gene frequencies of NA1 and NA2 were 0.56 and 0.44 respectively. There are no cases of alloimmune thrombocytopenia and neutropenia in newborns from the 200 studied women. CONCLUSIONS: The differences in genotype frequencies among platelet glycoprotein IIIa-specific antigens and in the gene frequencies of NA in Koreans are shown as compared with other ethnic groups. Therefore it is needed to find the proper screening target antigens and antibodies for Korean NATP and NANP patients.