Immunohistochemical staining and activity of ornithine decarboxylase in colorectal cancer

Using a new anti-human ornithine decarboxylase (anti-hODC) monoclonal antibody, the relationship between the immunoreactivity of ODC and its activity was analyzed in 21 human colorectal cancer tissues, 42 adjacent nontumorous mucosa specimens, and 10 normal rectal mucosa samples from frozen sections and paraffin-embedded samples. A statistical significant correlation was found between the antibody reaction and the enzymic activity ( P < 0.01). The immunohistochemical staining for ODC provides a new and simplified procedure for studying the activity of ODC as compared to previous methods using radioisotopes. It offers the advantages of retrospectively determining the amount of ODC in samples previously embedded in paraffin.