Frequency of fetal-maternal microchimerism: an analysis of the HLA-DRB1 gene in cord blood and maternal sample pairs

Purpose: We aimed to investigate the frequency of fetal-maternal microchimerism among cord blood (CB) from a Korean population. Materials and methods: We previously developed a nested polymerase chain reaction-single- strand conformation polymorphism method for microchimerism detection that is highly sensitive (0.01-0.001%) and specific. We used this method to investigate the frequency of fetal-maternal HLA-DRB1 microchimerism among 153 maternal and 152 CB samples. Results: Among the tested pairs, 41.1% exhibited at least one direction of microchimerism, 32.0% of the mothers possessed fetal microchimerism, and 23.4% of the newborns possessed maternal microchimerism. The overall microchimerism frequency was 28.2%. Conclusions: We hypothesize that the different microchimerism frequencies among population and methods are due to differences in detection specificities and subject characteristics. This study provides basic data on fetal-maternal microchimerism that may be useful for future studies on autoimmune disorder and virtual phenotyping in transplantation.