Development of IgG subclasses in healthy Polish children.

To determine the ontogeny of IgG subclasses in healthy Polish children IgG1, IgG2, IgG3, IgG4 concentrations were measured by enzyme-linked immunosorbent assay in 30 cord blood sera and sera from 152 healthy children aged 4 months to 16 years. The geometric mean of concentrations all of IgG subclasses in age-related groups of children were calculated. In cord sera, four IgG subclasses were found with the IgG1 level reaching about 90%, IgG2--52%, IgG3--80% and IgG4--33% of the mean adult values. In the group of youngest children (4-6 months of age) the concentration of all IgG subclasses were significantly decreased in comparison to initial values. Then, IgG1 and IgG3 levels increased rapidly reaching ca. 50% of the mean adult values by 1 year of age. We also demonstrated much slower maturation of IgG2 and IgG4 which lagged behind IgG1 and IgG3 development, especially in younger children.