Serum IgG to brain microvascular endothelial cells in multiple sclerosis.

Serum IgG to brain microvascular endothelial cells (BMECs) were assessed in the sera from 50 patients with definite multiple sclerosis, 24 patients with other inflammatory and non-inflammatory neurological diseases and 30 healthy individuals. Standard indirect immunofluorescence on BMEC culture was used as the bioassay system. Positive immunostaining was found in the sera (1:5 to 1:50 dilution) from 0/15 inactive relapsing remitting (RR), 12/16 active RR (p = 0.0001), 1/8 relapsing progressive (RP) and 0/11 primary progressive (PP) patients. No specific binding was detected when sera from neurologic and healthy controls were used. The specificity of the immune reaction for brain endothelium was established by the absence of staining on human umbilical vein endothelial cell and brain pericyte cultures. Gadolinium (Gd)-enhanced magnetic resonance imaging of the brain and spinal cord was performed in 36 MS patients within a 10-day interval from serum collection. Anti-brain endothelium antibodies were found in 9/12 patients with, and in 1/24 patients without Gd-enhanced lesions (p = 0.00002). Regardless of a pathogenetic role in the blood-brain barrier breakdown, serum IgG to BMECs may be a marker of disease activity in RR and RP MS and a factor differentiating RR/RP and PP MS.