Induction of experimental autoimmune myasthenia gravis with acetylcholine receptors using a nonionic block copolymer as adjuvant.

To induce autoimmune diseases in animals, the auto-antigen has to be emulsified in adjuvants (e.g., complete Freund's adjuvant) containing microbial products such as Mycobacterium tuberculosis. But these powerful immunoadjuvants are not without undesirable immune response to the microbial proteins and induction of adjuvant arthritis, which could interfere with the antigen specific autoimmune response to be tested. This study was performed to evaluate the requirement of microbial products in the induction of experimental autoimmune diseases, and to identify an adjuvant without unwanted immune responses. C57BL/6 mice were inoculated with Torpedo acetylcholine receptors (T-AChR) emulsified in Titermax (TM), an adjuvant containing nonionic block copolymer and no microbial products, and evaluated for experimental autoimmune myasthenia gravis (EAMG) susceptibility. Mice immunized with T-AChR in TM demonstrated characteristic myasthenic muscle weakness with electrophysiological defect, elevated serum anti-AChR antibodies, and muscle AChR loss. None of the mice that received TM alone had muscle weakness, serum anti-AChR antibodies or muscle AChR loss. The data imply that microbial products are not critical in the induction of autoimmune diseases like myasthenia gravis in mice. Further, nonionic block copolymer could be an ideal adjuvant in the induction of autoimmune diseases in animals.