The concentration of interleukin-1-beta (IL-1β; y-axis, picograms/milliliter) measured in the epidural space overlying the L5 DRG at baseline (Time=0hr) and 3, 6 and 24 hr after the application of saline (N = 15), autologous nucleus pulposus (NP=15) or NP + a neutralizing antibody to interferon-gamma (anti-IFNγ; N=18). ## p<0.005 at T=3, 6, 24hr compared to T=0hr.