Cytotoxicity of cytokeratin monoclonal antibody against keratinocytes: a possible therapeutic adjunct for cholesteatoma?
HYPOTHESIS: Monoclonal antibodies directed against cytokeratin subtypes in cholesteatoma produce growth inhibition of keratinocytes. BACKGROUND: Despite elegant surgical procedures for cholesteatoma, residual disease is an important clinical problem. Although gross cholesteatoma removal usually is feasible, microscopic foci of residual keratinocytes may develop into clinically significant disease. This study was designed to evaluate the keratinocyte cytotoxicity of monoclonal antibodies directed against a cytokeratin subtype relatively unique to cholesteatoma. METHODS: Keratinocytes and skin fibroblasts were trypsinized, counted, and seeded in multiwell plates. The cells were exposed to mouse monoclonal antibody to cytokeratin 10 at dilutions of 1:10, 1:25, 1:50, 1:100, and 1:200 with six replicates. After 24-, 48-, and 96-hour incubations, cells that had been pulsed with 3H-thymidine were harvested. Cellular DNA was processed for quantification of 3H-thymidine incorporation with a beta scintillation counter. Cells exposed to antibody are reported as percent inhibition relative to controls. RESULTS: Inhibition ranged from 88.9% for the 1:10 concentration to 26.9% for the 1:200 concentration after 24 hours of incubation. Similar effects were noted at the 48- and 96-hour intervals. Overall, the effect was significantly more pronounced on the keratinocytes than inhibition on skin fibroblasts. CONCLUSIONS: These results suggest that monoclonal antibodies have in vitro activity against keratinocytes. Additional investigation of a possible role for cytokeratin monoclonal antibodies should be pursued with a goal of developing a clinically useful biologic adjunct for cholesteatoma management.