Comparison of different monoclonal antibodies for the immunohistochemical assessment of cell proliferation in routine colorectal biopsy specimens.

In a series of paraffin-embedded colorectal biopsy specimens the monoclonal antibodies 19F4 and PC10 against the proliferating cell nuclear antigen (PCNA) and the antibody mib1, which recognizes the Ki67 antigen in formalin-fixed material, were compared with the Ki67 method on equivalent frozen sections to assess the applicability of these 'proliferation markers'. A high correspondence was found between the localization of the mib1 and the Ki67 immunoreaction product, associated with a highly significant quantitative correlation of the two indices (r = 0.70, p < 0.001). In contrast, after formalin fixation the two PCNA antibodies additionally stained cells outside the proliferative compartment so that a reliable assessment of cell proliferation was only possible after controlled paraformaldehyde or methacarn fixation. In the routine material mib1 was superior to PC10 because of its ability to distinguish the differences in cell proliferation among normal colorectal mucosa (29.1 +/- 6.8% positive cells), adenomas (43.3 +/- 10.6%), and carcinomas (52.9 +/- 8.7%), which PC10 did not possess (normal, 41.4 +/- 5.6%; adenomas, 37.5 +/- 8.7%; carcinomas, 51.5 +/- 8.2%).