Figure 2.

Distribution, morphology, and co-localization of CD68+ and CCR5+ cells in EA and LA zones of demyelination. Immunohistochemistry for CD68 (A and D) and CCR5 (B and E) was performed on serial sections. Additionally, dual-label immunofluorescence histochemistry for CD68 and CCR5 and confocal microscopy were performed (C and F). CCR5 immunoreactivity is shown in green; red indicates CD68 immunoreactivity. Shown are areas of EA (A–C) and LA (D–F) demyelination of a single lesion. Scale bars, 100 μm. BV indicates blood vessel. A: In EA areas two populations of CD68+ cells were found: perivascular cells (arrows) with the appearance of monocytes and parenchymal cells (arrowheads) exhibiting the morphology of activated microglia. B: CCR5+ cells in EA areas were predominantly perivascular with morphological character of monocytes (arrows). C: In EA areas CCR5+/CD68+ cells were predominantly perivascular and exhibited the morphology of activated monocytes (arrows). CCR5−/CD68+ cells in EA regions were parenchymal cells with the morphology of activated microglia or small phagocytic cells (arrowheads). Within EA areas only occasional CCR5+/CD68+ cells were detected in the parenchyma (double arrowheads). D: No distinct subpopulations of CD68+ cells were found in LA zones, which contained a homogeneous population of large, CD68+ phagocytic macrophages (arrowheads). E: CCR5+ cells in LA areas resembled large phagocytic cells (arrowheads) and were predominantly found in the parenchyma. F: Concomitant with the transition from EA to LA areas of demyelination, there was a dramatic change in distribution, morphology, and frequency of CCR5+/CD68+ cells. CCR5+/CD68+ cells in LA regions formed a homogeneous population of parenchymal (double arrowheads) and perivascular (arrow) phagocytic macrophages. CCR5−/CD68+ cells were rarely found (arrowhead).