Figure 3.

Complement Component Expression in MS tissue. We quantified the number of (A) C1q and (B) C3b immunostained cells of all types in normal and lesion cores. Panel A; box plots revealed a significant increase in C1q positive cells in WML tissue and in GML tissue compared with normal appearing WM and GM, respectively. C1q IHC shows immuno‐positive cells with astrocytic morphology in WML of case MS225, neuronal morphology in GML from case MS272 and an absence of staining in NAWM (case MS203) and NAGM (case MS230). Inset: In situ hybridization shows neurons (arrow; brown DAB reaction product) positive for complement C1QA mRNA (a), while the scrambled probe (ISH) is negative (b). All neurons are identified by expression of HuC/D protein by immunohistochemistry (blue reaction product). Panel B; Quantification of C3b positive cells. There was a significant increase in the number of C3b positive cells in WML tissue and in GML tissue compared with normal appearing WM and GM, respectively. IHC shows glial C3b staining from WML of case MS225 (arrows mark positive glia), neuronal and glial staining from GML and GM of case MS272 (inset shows magnified neuron indicating cytoplasmic and surface staining patterns). A decrease in cellular staining is shown in WM from case MS230. Inset: In situ hybridization shows neurons (arrow, brown DAB reaction product) express the mRNA transcript for complement C3 (a) while the ISH sense probe for C3 is negative (b). All neurons are identified by expression of HuC/D protein by immunohistochemistry (blue reaction product). Median, IQR and full range of data shown. Abbreviations: NAGM; normal appearing gray matter, NAWM; normal appearing white matter, WM; white matter, GM; gray matter.