Age-related changes in the levels of IgG, IgM and IgA antibodies to type I collagen in the sera of normal human subjects.

Serum samples from healthy subjects of different ages (within the age range of 1-75 years) were tested for the presence of anti-type I collagen (anti-CI) IgG, IgM and IgA by enzyme-linked immunosorbent assay (ELISA). All the tested sera showed anti-CI antibodies from the three immunoglobulin classes with the following age-related regularities: 1. Anti-CI IgG and IgM showed statistically non-significant changes up to the age of 60 decreasing thereafter.