Clinical analyses of GFAP autoantibodies in severe TBI and control subjects.

(A) Day 4–10 serum GFAP-BDP (38 kDa) autoantibody levels from severe TBI patients were semi-quantified and found to be significantly higher than those from normal controls. (B) Receiver Operating characteristic (ROC) curve plotting serum autoantibody levels to 38 kDa GFAP-BDP revealed that autoantibody level was a good discriminator between TBI subjects and healthy normal controls with AUC = 0.78. The average serum autoantibody levels at a cutoff of >8.49 arbitrary unit has a 64% sensitivity, 85% specificity, to distinguish between TBI and controls. (95% CI 0.70–0.87. AUC = area under receiver operating characteristic curve). (C) Frequency of autoab against 38 kDa GFAP-BDP in TBI serum (Day 4–10; n = 53) as compared to normal controls (n = 96). *Autoantibody positive represents a discrete immunoreactivity band signal of at least 1.50 densitometric units after background subtraction. (D) GFAP-BDP autoantibody correlated significantly to serum GFAP levels at 24 h post-TBI measured by sandwich ELISA. (E) A significant correlation between the best GCS score (index of severity) during the first 24 h after injury and GFAP-BDP autoantibody levels (GCS 3–8 are severe, GCS 9–13 moderate). (F) GFAP-BDP autoantibody levels at Day 4–10 correlated to outcome measurement GOS-E at 6 months.