Interleukin-4 deficiency facilitates development of experimental myasthenia gravis and precludes its prevention by nasal administration of CD4+ epitope sequences of the acetylcholine receptor.

Immunization with acetylcholine receptor (AChR) causes experimental myasthenia gravis (EMG). We investigated EMG in interleukin (IL)-4 knock out B6 (KO) mice, that lack Th2 cells. EMG was more frequent in KO than in wild type B6 mice. KO and B6 mice developed similar amounts of anti-AChR antibodies. They were IgG2a and IgG2b in KO mice, IgG1 and IgG2b in B6 mice. CD4+ cells from KO and B6 mice recognized the same AChR epitopes. Nasal administration of synthetic AChR CD4+ epitopes reduced antibody synthesis and prevented EMG in B6, not in KO mice. Thus, Th2 cells may have protective functions in EMG.