To further investigate complement dysregulation in tauopathy brain, quantitative sandwich ELISAs were developed and used to measure complement proteins (C1q, C3, FB), regulators (FI, clusterin) and activation products (C3b/iC3b, Ba, TCC) in grey matter brain homogenates, the same donor tissue used in IHC analysis (Figure 5). Here, CFI is linked to tauopathy.