I've thought about this and have come to the conclusion that heated molten paraffin is more of a "Dry" heat where the presence of water is virtually absent.  Using an aqueous solution to heat up things for antigen retrieval  is done in a "wet" heat where the presence of water is abundant... Therefore if we use dry heat we are removing more of the "bound" water and causing more antigen "masking" if you like.. Using the wet heat retrieval systems, we do not remove any more of the molecularly bound water, but possibly add some to the protein systems thereby "retrieving" the antigenicity if the antigen...

Just a thought on my part.

Mark Lewis
Technical Specialist
Shandon
1-800-245-6212 ext. 4013

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From:  Allison@cardiff.ac.uk [SMTP:MIME :Allison@cardiff.ac.uk]
Sent:  Thursday, August 05, 1999 3:43 AM
To:  john.e.love1@jsc.nasa.gov
Cc:  histonet@pathology.swmed.edu
Subject:  Re: Paraffin embedding and immunocytochemistry

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John,
Simple question you raised.  We are working on the answer - not easy but
very interesting!
If the heat of molten paraffin "destroys" immuno-reactivity, how come we
use heat for antigen retrieval?
Russ Allison, Wales