The Effect of Aging on Human Serum Immunoglobulin Concentrations

Abstract

Single radial diffusion was used to measure the concentration of IgG, IgA and IgM in sera of 811 healthy individuals aged from birth to 92 years. Evaluation of age, race and sex differences was accomplished by multivariate analysis on log_e transformed data using age as a linear covariate for each race-sex group within the 0 to 13, 14 to 27, 28 to 54 and 55 to 92 year age spans. Age contrasts between all groups were highly significant (p < 0.0001), while race and sex contrasts within all groups revealed only a significant difference in IgG related to race (p < 0.0133). Maximum serum immunoglobulin concentrations were reached in the third decade. Highly significant changes related to aging occur in older individuals as well as early in life. Average IgM concentrations decreased significantly by the sixth decade (p < 0.0005). Average IgG decreased significantly from the third through the sixth decade (p < 0.0027). Changes in serum IgA after maturity were small and not significant. These observations document the occurrence of a relative hypoglobulinemia in healthy older individuals.