We investigated whether matrix metalloproteinase-2 (MMP-2) is induced in peripheral blood T cells after their contact with tumor necrosis factor-alpha (TNF-alpha)-stimulated glioblastoma cell line (T98G), expressing vascular cell adhesion molecule-1 (VCAM-1), in patients with HTLV-I-associated myelopathy (HAM) compared to control patients with other neurological disorders (OND). Gelatin zymography revealed that the incremental ratio of gelatinolytic activity of MMP-2 in culture supernatants derived from T cells cocultured with TNF-alpha-stimulated T98G to that of supernatants derived from cultures of T cells alone was significantly higher in HAM patients than in control patients with OND. Immunoblot analysis of immunoprecipitates of culture supernatant showed that increased gelatinolytic activity of MMP-2 was due to increased production of MMP-2 protein in T cells. Increased gelatinolytic activity of MMP-2 in T cells of HAM patients was blocked by pretreatment of TNF-alpha-stimulated T98G with anti-VCAM-1 antibody before coculture with T cells, indicating that MMP-2 induction was VCAM-1-mediated. Although no significant differences were noted in the percentage of VLA-4-positive cells in cultured T cells between HAM patients and control patients with OND, our results indicate that VCAM-1-mediated MMP-2 induction is up-regulated in T cells of HAM patients.