Effect of MK801 treatment on T-cell infiltration. By immunohistochemical analysis we analyzed leukocyte infiltration. There was no staining for CD4+ in spinal cord obtained from Sham mice (a). Instead positive staining for CD4+ cells was observed in the spinal cord tissue collected from SCI-mice (b), on the contrary CD4+ lymphocytes infiltrates were significantly attenuated in MK801(2 mg/kg 30 min and 6 h after SCI induction)-treated mice (c). Densitometry analysis of immunohistochemistry photographs (n = 5 photos from each sample collected from all mice in each experimental group) for CD4+ (d) from spinal cord tissues were assessed. Figure is representative of at least 3 experiments performed on different experimental days. Data are expressed as % of total tissue area. Data are means ± s.e. of 10 mice for each group.*p < 0.05 vs. Sham. °p < 0.01 vs. SCI. ND: not detectable.