TREM2 and Alzheimer disease: Utilising IHC staining, colocalisation of DAP12 (Fig. 5g), HLA-DR, DP, DQ (Fig. 5h), TREM2 (Fig. 5i), and CD45 (Fig. 5j) was observed in IBA1+ microglia in both control and AD brains, demonstrating that PU.1-regulated genes are expressed by human microglia in situ.