Active matrix metalloprotease-9 in and migration pattern of dendritic cells matured in clinical grade culture conditions.

Dendritic cells (DC) represent potent antigen presenting cells (APC) that are capable of generating tumor-specific immunity. In DC-based vaccination the migration of the infused DC from the site of injection to the secondary lymphoid organs might be critical to induce an effective immune response. Therefore we analyzed the migrating properties of maturing DC generated from human blood monocytes under culture conditions in compliance with the good manufacturing practice (GMP) guidelines. Highly purified CD14+ monocytes were differentiated into immature DC (iDC), then optimally matured as evidenced by CD83 expression. Time-lapse videomicroscopy and Transwell migration assays performed with or without Matrigel, proved mature DC (mDC) to be highly migrating cells compared to iDC although mDC migratory response varied markedly according to individuals (n= 15). Moreover, as shown by gelatin zymography and ELISA, mDC predominantly expressed both the active form of the matrix metalloprotease-9 (MMP-9) and low amounts of its physiological inhibitor, the tissue inhibitor of metalloprotease-1 (TIMP-1) which may explain their high migrating capacity through Matrigel layers. Macrophage inflammatory protein-3beta (MIP-3beta), strongly increased mDC migration through Matrigel by up-regulating the membrane MMP-9 active form suggesting that injected mDC could be selectively guided to T-cell areas of lymph nodes by this chemokine. Taken together, we demonstrate for the first time that mDC, but not iDC, prepared in clinical grade conditions are both physiologically invasive cells expressing chemokine-active and -sensitive MMP-9, which may be critical for their trafficking through tissues after injection. Consequently, we argue that migration characteristics should be included into a gold standard for DC administrated to patients.