Background: Classical Hodgkin lymphomas are characterized by relatively few tumour cells and prominent proliferation of plasma cells, histiocytes, lymphocytes and eosinophils. In addition there is a varying degree of sclerosis, which is especially prominent in nodular sclerosis. These morphological peculiarities led to the idea that the interaction between tumour cells and bystander cells as well as the extracellular matrix may be important in Hodgkin lymphomas.
Materials and methods: Thirty-four classical Hodgkin lymphomas (CHL) were analysed regarding the expression of EMMPRIN, MMP-2, -7, -9, -10 and-11 using immunohistochemistry.
Results: The tumour cells were positive for EMMPRIN in 100% of the cases. In 82% of CHL the Hodgkin and Reed-Sternberg cells (HRS) were negative for MMP-2. In contrast the surrounding non-neoplastic cells were MMP-2-positive in 71% of the cases. The HRS cells stained positive for MMP-7 in 68% of CHL, whereas only a few surrounding cells were positive for this marker. In all but one case (97%) the HRS cells were negative for MMP-9. However, the surrounding cells stained positive in 32%, thus resembling the staining pattern for MMP-2. Only scattered cells of both populations, HRS cells as well as bystander cells, stained for MMP-10 and -11, and no specific staining pattern was observed.
Conclusion: Our data indicate a complex interaction between tumour cells and bystander cells with regard to metalloproteinases. The expression of EMMPRIN in the tumour cells may induce the expression of MMP-2 in the surrounding non-neoplastic cells. MMP-2 can be activated by MMP-7, which is expressed in the tumour cells. It is tempting to speculate that an interruption of this cycle could be of therapeutic benefit.