Natural autoantibodies (NAAs) that recognize autoantigens are mainly generated in the absence of any apparent immunization with foreign antigens (Ags). These antibodies maintain the body homeostasis through functions, such as inhibition of tumor angiogenesis, detection of structural changes in autoantigens, and exertion of anti-inflammatory impacts. The human body is shown to go through immunological and physiological changes during aging. However, data regarding the potential variations in the binding activity of NAAs is still scarce. Therefore, in this study, we were about to explore the trend through which the reactivity of serum NAAs with several autoantigens varies with advancing age.

Serum samples were prepared from healthy individuals of seven age intervals: (0) cord blood, (1) infancy, (2) childhood, (3) adolescence, (4) early adulthood, (5) middle adulthood, and (6) late adulthood (the elderly). The mean immune reactivity (MIR) of the sera with 24 human autoantigens that were obtained from Immunculus research center (Russia) was determined using ELISA and inter-group comparisons were also performed.

In general, the MIR of serum natural antibodies with the autoantigens was shown to follow an upward trend with advancing age so that the lowest and highest MIRs were detected in the cord blood and late adulthood samples, respectively. Moreover, the results of the inter-group comparisons indicated that the MIRs of the first, second, fourth, and sixth groups were significantly higher than those of their previous groups, i.e. zero, first, third, and fifth groups, respectively.

This study showed that the reactivity of human tissue-specific and non-specific NAAs with autoantigens varied along with aging. Regarding the crucial roles NAAs play in maintaining the body homeostasis, the variation in their concentration at different age intervals might account for the immunological and pathological changes that occur in the elderly.