Interleukin-2 receptor expression in canine cutaneous mast cell tumors

The prognostic assessment and therapeutical strategies of canine MCT depend highly on the biological behavior of these tumors which is mainly correlated with histological grade. However, despite the presence of c-KIT mutations little is known about underlying molecular mechanisms for MCT development and malignant progression that could be responsible for the diverse malignant behavior of these tumors. Recently, the IL-2R α-subunit CD25 has been introduced as a marker to distinguish neoplastic from non-neoplastic human mast cells in SM patients which leads to the assumption that the IL-2R may have an impact on the development and tumor growth of neoplastic mast cell diseases. The aims of this project were therefore to evaluate CD25 as a possible tumor marker for canine MCT, to investigate the expression of the remaining subunits and the ligand of the IL-2R and to assess the usefulness of the IL-2R as a malignancy marker for canine MCT. Accordingly, the following hypotheses were tested in this work: First Hypothesis The IL-2R-α-subunit CD25 is expressed by canine cutaneous MCT and differentiates neoplastic from non-neoplastic canine cutaneous mast cells. Second Hypothesis The complete IL-2R and the ligand IL-2 are expressed by canine cutaneous MCT. The IL-2Ris increased in higher grade tumors and thus contributes to mast cell tumor proliferation.