[Pathogenesis of polymyositis (author's transl)].

There are few convincing arguments for a direct intervention of humoral immunity mediated by specific antibodies or circulating immune complexes. Arguments in favour of a cytotoxic reaction are stronger. The likelihood of an infectious origin is supported by the presence of cell inclusions resembling myxovirus or picorna virus of the coxsackie group, and toxoplasmas may also be involved. The high incidence of associated cancers has given rise to speculations on the relationship between the two diseases, such as: myotoxic substances secreted by malignant tumours, delayed hypersensitivity reaction to a common antigen, or different effects of a single hypothetic causal agent.