Sex- and age-dependency of IgG auto-antibodies against IL-1 alpha in healthy humans

Eur J Clin Invest. 1994 Mar;24(3):212-8. doi: 10.1111/j.1365-2362.1994.tb00991.x.


Naturally occurring anti-interleukin (IL)-1 alpha IgG antibodies (Ab-IL-1 alpha) were measured in sera of 466 healthy Danish blood donors. Ab-IL-1 alpha bound IL-1 alpha with exceptionally high affinity (Kd: 10(-11) M) and neutralized both cell-associated and extracellular IL-1 alpha but not IL-1 beta or IL-1 receptor antagonist. More than 80% of the saturable binding of rIL-1 alpha to serum was to Ab-IL-1 alpha, suggesting that these antibodies are the quantitatively most important IL-1 alpha-binding components in serum. Judged by second antibody precipitation assay, the prevalence of Ab-IL-1 alpha varied between 30% and 75% and correlated positively with age (P = 0.037). The binding capacity of serum also increased with age. Although men were more frequently positive than women (P < 0.001), there were no sex- or age-dependent alterations in the average affinities of the antibodies. Free IL-1 alpha-like molecules were generally not detected in these sera. However, acid treatment showed that 25% of Ab-IL-1 alpha-positive sera contained low amounts of IL-1 alpha-Ab-IL-1 alpha immune complexes. IgG4 represented the main IgG isotype, whereas IgG3 Ab-IL-1 alpha were undetectable. The relative amounts of IgG4 Ab-IL-1 alpha increased while IgG2-and IgG1 Ab-IL-1 alpha decreased in elderly individuals. The presence in normal individuals and the lack of affinity maturation with age suggest that Ab-IL-1 alpha may be regulatory natural auto-antibodies perhaps coded by germline genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Antigen-Antibody Complex / blood
  • Autoantibodies / blood*
  • Female
  • Humans
  • Immunoglobulin G / blood*
  • Immunoglobulin G / classification
  • Interleukin-1 / immunology*
  • Male
  • Middle Aged
  • Sex Factors


  • Antigen-Antibody Complex
  • Autoantibodies
  • Immunoglobulin G
  • Interleukin-1