S100A8 is expressed in multiple cell types in the parietal cortex of patients with sepsis. S100A8 immunoreactivity does not colocalize with Iba1+ microglia (A) but does strongly colocalize with perivascular Iba1+ cells, likely infiltrating myeloid cells (B, E). S100A8 is also expressed in astrocytes (C, F). Apparent perivascular S100A8 immunoreactivity is adjacent to, but does not colocalize with the endothelial marker ZO-1 (D, G).