Relation of disease duration and T-cell proliferative responses induced by aggrecan, fibrillin, and matrix metalloproteinase (MMP)-3. Proliferative activity of peripheral blood mononuclear cells from patients with juvenile idiopathic arthritis was dichotomized as follows: stimulation index (SI)-non-responsive < 2 ≤ SI-responsive. Responders to the aggrecan peptide had the lowest disease duration (p = 0.016). Responders to the MMP-3 peptide showed a similar trend, which was close to reaching statistical significance (p = 0.056). Black bars: responders; transparent bars: non-responders. Asterisk indicates significant difference.