We further measured the total levels of IFN-γ in the lumbar spinal cord at selected times (day 0 (naive), 3, 7, and 14) after L5Tx or sham surgery in both WT BALB/c and BALB/c CD4 KO mice via ELISA. First, no significant differences between the L5Tx and sham treatments were detected within either of the genotypes (Figure 3, one-way ANOVA for WT mice, p=0.685, and for CD4 KO mice, p=0.601). Therefore, further statistical analyses were performed on all data using “time” and “genotype” as factors regardless of treatment. It was found that CD4 KO mice expressed significantly lower levels of IFN-γ in the lumbar spinal cord compared to WT mice at all-time points, while there were no significant changes in the total levels of IFN-γ detected within either genotype over time, (Figure 3, two-way ANOVA, pgenotype<0.001, ptime=0.146, pgenotype × time=0.243). In addition, IFN-γ was not detectable in the splenic tissue of any of the mice. These data support that a reduction in IFN-γ levels (which can be associated with a blunted Th1 response) may contribute to the observed reduced mechanical hypersensitivity in CD4 KO mice compared to WT mice following L5Tx [4].