CCL2 and myeloid sarcoma: When we compared CCL2 immunoreactivity in WM and GM of control subjects, MS patients without hippocampal lesions and MS patients with active or inactive lesions, we found significantly more CCL2 positive cells in hippocampal WM (6.6 ± 9.1 cells/mm2) than GM (1.0 ± 2.9 cells/mm2) of control subjects (Wilcoxon Signed Rank test, p = 0.04).