CD68 and neoplasm: Moreover, immunohistochemical staining with the CD68 pan-macrophage marker revealed a specific intense positivity in both brain hemispheres of OV-treated mice in the area of tumor cell injection, in part overlapping the area of CD11b and IBA-1 positive cells, notably, in the left hemisphere at the site of oHSV-1 injection (Fig. 6, oHSV-1; CD68), while in the opposite hemisphere, a significant population of CD68 + amoeboid cells were distributed extensively throughout the neoplastic bed (Fig. 6, challenge; CD68).