Muscle cells under attack

Antitumor T cells may confuse regenerating muscle cells for their intended targets and attack them, according to new data from Casciola-Rosen et al. (page 591). This unsolicited attack may be the trigger for a self-perpetuating autoimmune muscle disease.Many proteins that are targeted in tissue-specific autoimmune diseases are expressed throughout the body. In most cases, the mechanisms that preferentially guide the autoreactive cells to the target tissue are not understood. An autoimmune muscle disease known as dermatomyositis is a good example. The helicase protein Mi-2 has been associated with dermatomyositis, but its expression in muscle and its function in the pathology of disease had never been explored.

Casciola-Rosen and colleagues now show that muscle cells from patients with dermatomyositis, but not those from healthy controls, expressed high levels of Mi-2 and other myositis...