Leukocyte elastase in murine and human non-Hodgkin lymphomas

Extracellular proteases play a crucial role in the invasive behavior of nor mal and transformed leukocytes. Thus far, however, most of the attention ha s been focused on members of the family of matrix metalloproteinases. In th is work, we show that lymphoma cells can express leukocyte elastase (LE) an d recruit the enzyme at their surface via ICAM-1. The expression of LE by l ymphoma cells was augmented significantly by stimulation with IL-6 and IL-1 3, both of which also induced the expression of MMP-9. Although LE and IL-1 3 transcripts were detected in several non-Hodgkin's lymphomas, immunohisto chemical analysis of lymphoma tissues also showed that LE was strongly expr essed in infiltrating leukocytes. Given the spectrum of key molecules that can he cleaved by LE and that LE and MMP-9 are involved in the invasive beh avior of normal or transformed leukocytes, our results raise the hypothesis that LE plays a crucial role in the multistep processes of inflammation an d lymphoma metastasis.