Neuroelectric blocking factors in multiple sclerosis and normal human sera

Serum samples from 13 multiple sclerosis (MS) patients and ten normal human serum samples were applied to cerebral neocortex cultures and evaluated for their ability to block evoked electric activity. A high proportion of sera positive for neuroelectric blocking factors was found in both groups, and there was no substantial difference between serum samples from MS patients and those from normal human volunteers. Some of the neuroelectric blocking factors were thermolabile, others were thermostable, and still others may have been complement-dependent. It is concluded that the ability to block evoked electric responses in tissue cultures is a nonspecific serum property, and that it is not specifically related to the pathogenesis of demyelinating disease.