The results of cerebrospinal fluid agarose gel electrophoresis in 300 
consecutive patients were correlated with neurological examinations and 
diagnoses, other cerebrospinal fluid studies, and the results of evoked 
potential examinations. The presence of oligoclonal bands was the most sensitive 
test for multiple sclerosis (MS); bands were present in from 100% (11/11) of 
patients with definite MS to 82% (27/33) of those with possible MS (classified 
by McAlpine criteria). The visual evoked response was the next most sensitive 
study. Thirty-eight patients without MS or related disorders had bands in the 
IgG region. Three patients had plasma cell dyscrasias. Seven patients had thick 
single bands. Single bands did not correlate with chronic polyneuropathy but 
appeared to be an artifact of storage. Twenty-eight patients had active 
neurological disease, including cerebral infarction (in 5), viral infection (in 
4), remote effect of carcinoma (in 4), and acute and chronic polyneuropathies 
(in 6). In acute illnesses (i.e., vascular insults), repeat electrophoresis 
showed disappearance of bands. In continually active disease, bands persisted. 
These results indicate that the presence of oligoclonal bands provides sensitive 
supporting evidence for the diagnosis of MS but that bands may be present in 
other disorders, including those not directly related to infection or abnormal 
immune response. The data suggest that oligoclonal bands may represent an immune 
response to neurological injury that is prominent in disorders with a 
particularly intense or continuous antigenic stimulus.