C3 and myeloid sarcoma: Complement proteins (including C1q, C3), activation products (C4d) and their receptors, including anaphylatoxin receptors (C3aR1 and C5aR1), are located at subpial, leukocortical, white matter (WM) and deep GM areas in MS, where they associate with the extent of myelin and neuronal loss (Breij et al., 2008; Barnett et al., 2009; Ingram et al., 2014; Michailidou et al., 2015, 2017; Watkins et al., 2016; Loveless et al., 2018; Cooze et al., 2022).