Alloimmunization to Granulocyte Antigens among Korean Pregnant Women

Han, Tae Hee; Cho, Yong Kyoon; Han, Kyou Sup

Abstract

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).