ABSTRACT
PURPOSE: All IgG subclasses such as IgG1, IgG2, IgG3 and IgG4 can be transferred from mother to fetus through the placenta, though the amount of each IgG subclass is different from one another. Maternally acquired immunity might have an important role for the protection against the infections. We studied transplacental passage of IgG subclasses. METHODS: In this study, we observed the transplacental passage of IgG-subclasses in 22 paired samples of maternal and full- term fetal cord sera. Gestational ages varied from 37 to 42 weeks. The concentrations of IgG subclasses were analyzed by radial immunodiffusion method using commercialized Human IgG Subclass Combi kit. RESULTS: The concentrations of IgG subclasses, IgG1, IgG3 and IgG4 in cord sera exceed the maternal concentration, while IgG2 did not. The ratio of serum levels of cord to maternal were 1.330+/-0.067 for IgG1, 0.859+/-0.039 for IgG2, 1.258+/-0.058 for IgG3 and 1.159+/-0.038 for IgG4. CONCLUSION: This result suggested that the placenta may play a selective barrier for passage of IgG2.