Immunocytochemical localization of desmin at human neuromuscular junctions.

We localized desmin at human neuromuscular junctions (NMJs) using specific anti-desmin monoclonal and polyclonal antibodies. It was highly concentrated in the postsynaptic domain. It was found in all the NMJs examined. Compared with the area of acetylcholine receptors identified by bound alpha-bungarotoxin, the strong desmin immunoreactivity occupied a slightly larger area and was localized slightly deeper in the muscle fiber, suggesting that desmin might be accumulated within the postsynaptic folds and possibly below the folds. This appears to be the first identification of a protein unrelated to cholinergic transmission accumulated at human NMJs.