Normal serum concentrations of IgG subclasses in the Japanese adults

Normal values of IgG subclasses in the serum were measured by the specific monoclonal antibody-based ELISA technique with a Japanese healthy adult population (840 individuals comprising 306 male and 534 female) in their 2nd to 8th decade. The mean IgG 1 concentration in this population gradually increased linearily with increasing age although the mean levels of IgG 2, IgG 3 and IgG 4 showed no age-related significant variations. The percentages of individual IgG subclasses in the total IgG amount (as the sum of the four subclasses) revealed that the IgG 3 alone increased slightly with age. Possible differences in the percent composition of the IgG subclasses were sought between this population and a non-Japanese US healthy adult population. The percentages of IgG 1 and IgG 3 were approximately 8% and 2% lower but the IgG 2 was approximately 10% higher in the Japanese population than in the US population, with no significant difference in the IgG 4 between these populations.