Search for antibodies to skeletal muscle proteins in amyotrophic lateral sclerosis.

We have investigated serum from 16 patients with amyotrophic lateral sclerosis (ALS) and 15 patients with other neurological diseases (OND) for antibodies which react with skeletal muscle derived antigens. Two different preparations of skeletal muscle antigens were used: i) proteins released from rat diaphragm in organ culture and ii) proteins obtained from a muscle homogenate. We also compared antigen preparations from denervated and non-denervated muscles. A rabbit anti-serum reacted strongly with three proteins in both types of protein preparation, but none of these proteins were specific to denervated muscle. None of the 16 ALS sera could be shown to react with protein antigens from any of the muscle preparations. One of the ALS patients had an IgG lambda monoclonal protein in the setting of a multiple myeloma. This monoclonal protein did not react with protein antigen from rat muscle, human grey or white matter.