CD4 and neoplasm: Notably, systemic CpG-C administration did not affect infiltration of T cells (i.e., CD4+) or monocytes (i.e., CD68+) into the brain (Fig 4D), or the number of GFP+ cells (i.e., monocytes/microglia) evident in the brain 24 hours following administration of tumor cells (Fig 6F).