We therefore attempted to visualize C3b using antibodies that have been used to show C3 localization at synapses that are lost during developmental pruning, aging, and neurodegenerative disease.58–61 However, we failed to detect specific localization (Figure S7A) and note that previous studies, to our knowledge, have not shown synaptic C3 staining validated against C3 KO tissue. Here, C3 is linked to neurodegenerative disease.