Multiple sclerosis associated agent (MSAA): failure to confirm an association with multiple sclerosis.

Recent reports indicate that a multiple sclerosis agent (MSAA) has been isolated. This agent was detected in mice by a depression in the percentage of mouse polymorphonuclear neutrophils (PMNs). We attempted to repeat these studies using coded specimens. The test, itself, was extremely variable and difficult to reproduce. In the first study, three of three multiple sclerosis (MS) patients and one of two control patients' specimens showed some PMN depression. In a repeat study of these same samples, one of three MS patients and one of two controls were associated with PMN depression. With a second set of coded specimens, one of four MS patients, one of three patients with neurologic diseases, and none of three controls showed PMN depression. We were unable to confirm the presence of MSAA and conclude that the results were random.