Tumor necrosis factor alpha (TNFα) in human skin: a comparison of different antibodies for immunohistochemistry

Abstract Conflicting results have been reported regarding the localization and presence of TNFα in normal human skin. To study TNFα expression, we tested a panel of antibodies directed against human TNFα. First, antibodies were tested for immunoreactivity on cytospots of isolated LPS-stimulated peripheral blood mononuclear cells. Second, antibodies were tested to detect recombinant TNFα in Western blots. Some antibodies were found to be unable to detect recombinant TNFα in the blots. However, most antibodies were able to bind TNFα protein, but they did not bind to other irrelevant proteins that were also present in the blots. Finally, antibodies were tested on cryosections of normal human skin. Antibodies that did not react with TNFα in the blots were incubated with TNFα before the staining procedure to see whether these antibodies specifically bound TNFα. We found that, although all the antibodies bound TNFα, there were clear differences in staining patterns. This indicates that these antibodies may recognize distinct epitopes or different forms of TNFα. The differences found in this study and those reported previously could be the result of differences in the concentration of antibody used, the staining procedure or specificity of the antibody itself. So, for unambiguous interpretation of data, it is important to know the characteristics of the antibodies used.