I'm always wondering why some antibodies are only suggested to be applied to paraffin-embedded section, but NOT frozen section. In my eyes, if the antibody could reach the antigen on paraffin sections, that means it's even easier on frozen sections? What makes so different between those applications. somebody have explanations?
Also, If am having an antibody that's suggested to be used in IHC-P, is it OK if I used it in IHC-F??
Thanks!
The description "frozen" and "paraffin" is misleading. Better it should be "antibody for fixed or unfixed tissue/Antigens". FFPET. Proteins/Antigens change their conformation by fixation with formalin. Also the Dehydration-infiltration-process can lead to changes. This results in the fact, that most antibodies that recognise the native antigen don't recognise the fixed antigen. This can be partly restored by antigen-retrieval. In practice it may or may not work, that the antibody does its job on both.
I think the discrepancy you describe is generally just due to the manufacturer's experience - they may have tested their antibody (or received customer feedback) in IHC-P but not IHC-F, and therefore they only list IHC-P as a 'validated' approach. That doesn't mean it wouldn't work in IHC-F. The other possibility is that the antibody was raised by immunization against the formalin-fixed epitope. If the fixation has markedly changed epitope conformation, the non-fixed version might not be detectable with that antibody.
In any case, with any antibody-based detection assay, the real proof is in the pudding, ie. testing it yourself. You can't really trust the information that manufacturers provide (except for a very tiny minority of suppliers, the ones who actually care about the reliability of their product), and you have to figure it out for yourself, in the application that you want to use.
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