AGE-RELATED AND SEX-RELATED RESISTANCE TO CHRONIC EXPERIMENTAL AUTOIMMUNE MYASTHENIA-GRAVIS (EAMG) IN BROWN-NORWAY RATS

The influence of age and sex on the induction of chronic EAMG was anal ysed. Aged male rats, immunized with Torpedo acetylcholine receptor (t AChR), showed no clinical signs of disease or AChR loss. Immunization of young male Brown Norway (BN) rats resulted in both clinical signs o f disease and 65% AChR loss. In contrast, both young and aged female B N rats showed comparable AChR loss (58% and 50%, respectively), althou gh aged female rats did not develop clinical signs of disease. Differe nces in antibody titres, isotype distribution, fine specificity or com plement activation could not account for the observed resistance. Thes e results suggest that resistance against EAMG in aged rats is due to resistance of the AChR against antibody-mediated degradation, or to me chanisms able to compensate for AChR loss.