B-245 Novel monoclonal antibodies validated specifically for immunohistochemistry by performance assessment on tissue microarrays
Authors: Ball A , Hsieh Y , Huang C , Huang S , Wu S , Liu J , Peng P , Lin C 
Published: October 2024

Abstract

Background
Immunohistochemistry (IHC) is a laboratory immunoassay that is a pillar of diagnostic pathology, particularly in the identification and characterization of neoplasms and other diseases/disorders. Though performed routinely, rigorous SOP protocols must be determined empirically for each molecular target, beginning with antibody selection. Both traditional polyclonal and hybridoma-based monoclonal antibodies have been employed in the past, though monoclonal, and particularly recombinant monoclonal, antibodies are preferred. However, any reagent used for diagnostic purposes must be meticulously validated to minimize, if not eliminate, erroneous interpretations of IHC assays. Thus, the extent of validation is the pivotal aspect for establishing an antibody as a reliable diagnostic tool for IHC applications.

Methods
GeneTex has assembled an extensive catalog of rabbit and mouse monoclonal antibodies validated specifically for IHC. These antibodies are tested on both human normal tissue and cancer tissue microarrays, with upwards of 76 normal and numerous tumor tissues included. Images of the staining are available for all the tested tissues. This broad spectrum of tissues allows a researcher to assess the performance of the antibody on known positive and negative samples, thereby minimizing the risk of false positive or false negative readouts (Gown, 2016). In addition, the data images are of sufficient resolution to determine proper cellular localization of the signal. This special catalog of IHC-optimized reagents are listed under the “HistoMAX” designation. New antibodies will be added continuously, many of them being fully recombinant rabbit monoclonals manufactured using a multi-parameter FACS-based methodology to select antigen-specific IgG+ memory B cells from an immunized rabbit with subsequent cloning of the matched IgG heavy and light chains (Starkie et al., 2016). These recombinant antibodies will be validated following the same approach described above.

Results
Presently more than 130 mouse or rabbit monoclonal antibodies are available in the HistoMAX line of IHC-validated products and are directed against a spectrum of important targets. This includes antibodies for the commonly analyzed cytokeratins 5, 6, 7, 18, 19, and 20, among many others. Antibodies for CTLA4 and PD-L1 headline products for immunology and immunotherapy research, while other reagents are directed against various cadherins. Hormone receptor antibodies are also represented, with antibodies against estrogen receptor alpha, progesterone receptor, Her2/ErbB2, and the androgen receptor. There are also antibodies against various key “Cluster of Differentiation” (CD) proteins as well as other membrane proteins such as ACE2. Many antibodies are relevant to the study of human malignancies, such as CD66e/CEACAM5/CEA, MSH6, p63, MUC1, Collagen IV, EpCAM, PAX6, PAX8, GP2, TRIM29, S100, and GAD65. All antibodies were evaluated as described above.

Conclusions
Antibodies are application-specific reagents, and the best antibodies for IHC are validated through systematic staining of a multitude of normal and abnormal tissues. This is the only way that an antibody’s performance for IHC can be critically assessed. The HistoMAX reagents consist only of those monoclonal antibodies that have generated expected signals, or the lack of a signal, in a wide range of tissues in a manner consistent with the literature.