Confocal Immunohistochemistry of progranulin with cellular markers. (a-c). Cellular expression of PGRN (green) (a), microglial marker IBA-1 (red) (b) and colocalization of structures within microglia (yellow) (c) in a high plaque case. Green immunoreactivity that did not colocalize with IBA-1 (red) immunoreactivity identified cells with neuronal morphology. Scale bar represents 20 μm. (d-f). PGRN immunoreactivity (green) (white arrowheads) was present within cerebral vessels, but did not colocalize with the endothelial marker CD31 (red) in AD case. Scale bar represents 20 μm. (g-i). PGRN immunoreactivity (green) (g) did not colocalize with astrocyte marker GFAP (red) (I). Scale bar represents 20 μm. (j-l). Expression of PGRN (green) and microglial marker IBA-1 (red) associated with plaque structures of low plaque (J), high plaque (k), and Alzheimer’s disease (l). PGRN-positive microglia (yellow – arrows) are observed in microglia clustering and infiltrating PGRN- positive plaque-associated structures. Most of the PGRN immunoreactivity (arrowheads) appeared separate from DAPI-stained nuclei (DAPI – blue). Scale bar represents 30 μm.