Immunohistochemistry-Based Fluorescent Nanoparticle Assay for Determination of Antibody Binding Capacity and Its Correlation with Flow Cytometry Analysis

The determination of antibody binding capacity is crucial in the development of drug antibodies. Despite its widespread use, flow cytometry may only be used to evaluate single cells in solution. In addition, analyzing the antibody localization in tissue sections of animal models after drug administration, as in immunohistochemistry (IHC), is desirable. In this study, antibody-treated cells were fixed on glass slides, and their analysis was directly compared with flow cytometry. Cell-bound antibodies were quantitatively detected using a method that relies on phosphor-integrated dots (PIDs), which are highly brilliant nanoparticles applicable to immunohistochemistry. The outcomes of this approach were highly correlated with flow cytometry, suggesting that it is able to quantitatively detect cell-bound antibodies at a level comparable with flow cytometry. Therefore, this novel IHC-based technique is valuable for quantitative analysis and localization of antibodies in tissue sections of drug administration.