M30 Expression Demonstrates Apoptotic Cells, Correlates With In Situ End-Labeling, and Is Associated With Ki-67 Expression in Large Intestinal Neoplasms

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Abstract
Context.—The monoclonal antibody M30 recognizes a neoepitope of cytokeratin 18 produced during apoptosis. It is reactive in formalin-fixed, paraffin-embedded tissue and has great potential in the study of apoptosis in clinical and experimental material. Objectives.—To compare the results of M30 immunoexpression with a more established technique of demonstrating apoptosis in tissue sections, in situ end-labeling. A secondary objective was to compare the results with immunoexpression of the proliferation-associated antigen Ki-67. Design.—Retrospective analysis of adenomas and adenocarcinomas of the large intestine. Interventions.—Immunohistochemistry for M30 and Ki-67, and in situ end-labeling. Formalin-fixed, paraffin-embedded tissue was used. Main Outcome Measures.—The number of cells positive for M30, Ki-67, and in situ end-labeling, expressed as a proportion of the total number of cells counted. Results.—A strong positive correlation was found between in situ end-labeling and expression of M30, although the counts were widely scattered around the regression line. Counts of Ki-67 were strongly correlated with both M30 expression and in situ end-labeling. Immunoexpression of M30 was generally easier to interpret than in situ end-labeling, and the procedures for M30 immunohistochemistry were technically less exacting. Conclusion.—These findings support the application of M30 immunoreactivity in the study of apoptosis.