Development of anti-tissue antibodies in rats.

The sera of `normal' rats have been found to contain anti-tissue antibodies from shortly after birth. The antibody titres rose rapidly over the first 3 weeks of life reaching adult levels by the time the rats were 3–6 weeks old. Neonatal rats were rendered tolerant by exposure to bovine serum albumin (BSA). In contrast, higher levels of anti-tissue antibody were found in the sera of neonatal rats exposed to tissue antigens released by experimental liver damage than in the sera of littermate controls. It is suggested that the particulate nature of the tissue antigens may be associated with their ability to provoke an immune response in neonatal rats and that this in turn may be a factor hindering the induction of tolerance to these antigens.