C4B and Alzheimer disease: In the oligodendrocyte compartment, we identified AD-associated alterations of distinct cell subsets, such as the decrease in Ptgdshigh mature oligodendrocytes39,40 (OLG1) and the prominent increase in disease-associated oligodendrocytes41,42 (DOLs, C4b+ cells) and committed oligodendrocyte precursors (COPs; Fig. 2i, j).