MMP-2 and MMP-9 expression in adult and childhood acute lymphatic leukemia (ALL).

In the present study the expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in acute lymphatic leukemia (ALL) is studied with immunocytochemical staining in bone marrow aspirate smears from 75 patients. The material included 20 adult and 55 pediatric ALL patients. In 65% of the adult ALL cases the immunoreactive protein for either MMP-2 or MMP-9 or for both the enzymes was seen. A statistically significant correlation (P 0.027) with MMP-2 positivity and appearance of extramedullary infiltrates was found in adult ALL, suggesting that the gelatinase activity could be related with increased extravasation of the leukemic cells in ALL. This has to be confirmed in a larger patient population. In pediatric patients there were only seven cases (12.7%) out of 55 with positive immunostaining for either of these metalloproteinases. MMP expression correlated with L2 FAB class, high-risk tumor group and T-cell immunophenotype, but not with extramedullary presentation in pediatric patients with ALL indicating basic biological differences between adult and childhood ALL.