Oligoclonal immunoglobulin G in acute subarachnoid hemorrhage and stroke

Oligoclonal Ig bands were found in serum and CSF of 13 of 83 patients (16%) with verified subarachnoid hemorrhage (SAH). Serum Ig bands were more common in patients with SAH than in those with cerebral ischemia. The reverse was true with oligoclonal Ig bands in CSF. These patterns suggest that there are two different mechanisms and sites of IgG synthesis: an inflammatory process after acute stage of vascular damage and a latent immunologic process--ie, polyclonal B-cell activation by injury to the brain.