CD68 and amyotrophic lateral sclerosis: Immunohistochemistry was used to identify microglial markers HLA-DR, CD68, and Iba1, and pTDP-43 aggregates, in the control and ALS motor cortex including cases previously shown to have pTDP-43 in defined regions including the hippocampus (representing more advanced disease, ‘stage 4 ALS’) [63] and cases with pTDP-43 in the motor cortex and/or spinal cord but not hippocampus (representing less advanced disease, ‘stage 1–3 ALS’, Fig. 1A-E).