BACKGROUND: It has been known that blood group antibodies are not produced in the neonatal period and that if the antibodies exist, they are probably maternal in origin which had crossed the placenta. There have been several studies conducted abroad on when these antibodies are formed but none has been done in Korea. This study was carried out to determine the ABO blood type and blood group antibodies in children from neonates up to 5 year old. We hoped to determine when and in what pattern blood group antibodies were produced. METHODS: We selected 337 children from neonates up to 5 year old who were admitted to Hanyang university Hospital in Seoul or Kuri from 1994 to 1996. Cell typing was done immediately by the slide method. The anti-A and anti-B used for cell typing were supplied by Immucor (Norcrosis, Ga) . Sera were stored at -70 degrees C until they were tested for ABO blood group antibodies by the standard saline test tube method. When uncertain results were obtained, a drop of the mixture was placed on a slide and observed under a microscope. RESULTS: ABO blood group antibodies were detected in 9 of 50 (18%) infants less than 1 week old and in 10 of 51 (20%) infants between 1 week and 3 months of age. The pattern of ABO blood group antibody production was similar to that of the fetal period up to 3 months after birth, after which antibody production increased rapidly to reach approximately 80% at 6 months of age, There was no difference in ABO antibody production between boys and girls. The antibody formation pattern of group A and group B infants less than 6 months of age showed anti-A to be 35% and anti-B to be 20%. In group O infants of the same age, anti-A was positive In 42% and antral-B In 33%. However, after 6 months of age, there was no difference in antibody production among groups A, B, or O. CONCLUSIONS: Antibodies directed toward ABO antigens were detected in 19 out of 101 (19%) infants less than 3 months old. We therefore believe it is necessary to Perform serologic typing as well as cell typing in these Infants. Furthermore, the emergency transfusion of type A or B blood to a type O infant under the impression that anti-A and anti-B do not exist should be forbidden.
Antibodies* ; Antibody Formation ; Child* ; Child, Preschool ; Emergencies ; Female ; Hope ; Humans ; Infant ; Infant, Newborn ; Korea ; Parturition ; Placenta ; Seoul