Comparable antibodies

Comparing the signals generated by two independent antibodies for the same protein target in different samples is a practical way to test antibody specificity. This applies to various applications including western blot, immunoprecipitation, immunohistochemistry, and immunocytochemistry, among others. This “Comparable Antibodies” strategy is one of GeneTex’s “Five-Pillar Validation” methods for quality assurance. The following examples illustrate how this approach is utilized to verify antibody specificity.

In this example, A431 and A549 cells were cultured in basal medium for 24 hours followed by treatment with 100 ng/ml IFN-gamma for 48 hours. Whole cell extracts were then subjected to western blot using either GeneTex’s PD-L1 antibody (GTX104763) or a comparable antibody from an independent manufacturer following its recommended dilution factor. The signals were generated using the same HRP-conjugated secondary antibody and development parameters. The results demonstrate a consistent pattern and molecular size, representing PD-L1’s glycosylated form. Interestingly, only GTX104763 detects the unglycosylated PD-L1 in A549 cells (~ 33kDa), which was further confirmed by Tunicamycin treatment (see the GTX104763 data sheet for more information).

In another example, slides of human breast carcinoma tissues that express different amounts of HER2/ERBB2 were tested by immunohistochemistry with GeneTex’s HER2/ ERBB2 antibody (GTX100509) and a comparable antibody from another manufacturer. Both antibodies show the expected staining pattern and intensities that correlate with the respective expression levels for each sample. GeneTex antibodies that have been validated using this strategy will be labeled with the icon “”  in relevant product pages and marketing materials.