It is well established that natural autoantibodies are present in sera of healthy individuals and that the level of these antibodies changes with increasing age in humans. Evaluation of the total serum level of IgG and IgM as the main natural autoantibodies provides us with valuable information on their potential role in the aging process. This study aimed to evaluate and compare the changes in the total serum level of IgG and IgM in healthy individuals of different age groups.

Blood samples (n=270) were obtained and included in seven age groups ranging from cord blood to the elderly. The concentration of total serum IgG and IgM was assessed using nephelometry. Moreover, the association between the level of total IgG and IgM, and age was determined.

IgG concentration, despite a slight decrease in under 1-year-old infants, followed a rising trend with increasing age. On the other hand, the mean value of total IgM showed an increasing pattern from cord blood up to the middle age (40years) after which it started to decrease to its lowest level in the elderly. We also found that the drop in the level of IgM level after the middle age was in line with the changes in the frequency of blood B-1 cells, which we reported in our previous study.

Overall, this study showed that the mean serum levels of total IgG and IgM varied with age. In most cases, the differences between mean values of total antibodies at different age intervals were significant. The total amount of both serum IgG and IgM showed an increasing trend ranging from cord blood up to the middle age samples rejecting their role in physiological and pathological processes. Nonetheless, the declining trend observed for IgM from the middle age to the elderly could be partly responsible for the imperfect immune responses and higher rate of pathological disorders observed along with aging.