Neutralizing MIP-1α, MCP-1, GM-CSF, and TNF-α together results in marked reduction in the number of LPC-induced phagocytic macrophages. A, B, Mac-1 immunohistochemistry of longitudinal sections of the adult mouse spinal cord 4 d after injection of LPC along with either control antibodies (A) or all four neutralizing antibodies (B). In control animals, large, round Mac-1⁺ macrophages that have clear areas in the cytoplasm are seen (A). In contrast, very few of these Mac-1⁺ cells are seen in animals injected with LPC plus blocking antibodies (B). Sections were counterstained with Neutral Red. Scale bar, 80 μm. C, Quantification of Mac-1⁺ macrophages in the spinal cord 4 d after injections of LPC along with either control antibodies (■) or blocking antibodies (▪). Blocking MCP-1, MIP-1α, TNF-α, and GM-CSF together almost completely reduced the number of Mac-1⁺ macrophages induced by LPC. Mean ± SEM (*p < 0.001);n = 4 animals. Ab, Antibodies.