In vitro chemosensitivity testing of hematological cancers: immunohistochemical detection of ornithine decarboxylase

A new method for in vitro chemosensitivity testing of human lymphoma and leukemia patients has been developed. The method is based on the use of ornithine decarboxylase (ODC), a universal marker of proliferation, which is expressed early during the cell cycle and has a short half-life. This marker was detected by a quantitative immunohistochemical analysis, using an ODC antibody and a FITC-linked second antibody. The in vitro chemosensitivity of lymphocytes from four normal individuals was tested by the immunohistochemical method. Lymphocytes from 25 cancer patients were also examined. In drug-sensitive cells, the intensity of the marker declined in the presence of the drug, whereas resistance to the drug was demonstrated by the presence of the marker. A good correlation was found between the predicted chemosensitivity and the outcome of the therapy. It has been suggested that this approach could be used for in vitro chemosensitivity testing of hematological cancers and most likely also for other malignancies.