RE: [Histonet] Advice.

From:"Morken, Tim - Labvision"

Ian, The vast majority of antibodies can be frozen, but I think you are on
the right track in thinking the antibody manufacturer is trying to avoid
problems with freeze/thaw of the vial they sell. If you aliquot, you will
avoid that problem. However, if sodium azide is added, the refrigerator
shelf life can be years. Whether to refigerate or freeze depends on how fast
you will use the antibody up. Even if bacteria or mold grows it can often be
filtered out and the antibody performs fine.  For the most part, serum and
ascites can be aliquoted and frozen as-is (they are well buffered and have
loads of protein). Hybridoma supernatent requires addition of buffer, but
that is the manufacturers job. Purified antibody is generally ok to freeze
if at a concentration above 1mg/ml, but usually that is the concentration a
manufacturer works from. A user will have a much lower concentration and so
needs addition of a protein, such as 1% BSA to prevent adsorbtion to the
vial surface. Most of the time that is added by the manufacturer. If you buy
an antibody without azide or BSA you will have to consider that when storing
the antibody. Precipitates in frozen or sometimes even refrigerated
antibodies are usually cryoproteins that clump up. Filtering removes them
but leaves the antibody. In rare cases an antibody is a cryoprotein and will
precipitate. In those cases you cannot even refrigerate the antibody.
Glycerol does not "preserve" the antibody the same way azide does (prevent
organism growth), but stabilizes it in solution, as does BSA. Glycerol is
nice to use for freezer aliquoting, however,  because it stays liquid and
you don't have to wait for it to thaw. 

It may sound complicated, but in over 20 years I have only had a handful of
antibodies go bad from storage. In general if the antibody will be used up
within two years, then make sure it has azide and just keep it in the
fridge. If you want to keep it longer, aliquot and freeze. -20 is fine, but
-80 is better for really long term storage.

Tim Morken
Lab Vision / Neomarkers

-----Original Message-----
From: Ian Montgomery [] 
Sent: Friday, February 27, 2004 5:33 AM
Subject: [Histonet] Advice.

         Antibody, store at 4C, do not freeze, stable for 1 year. What's 
the current thinking. Are these antibodies affected by freezing? Or is it 
just the company covering themselves against users thaw/freezing. In the 
past I've just aliquoted and frozen anyway.

Dr. Ian Montgomery,
Graham Kerr Building,
Institute of Biomedical & Life Sciences,
University of Glasgow,
G12 8QQ.
Tel: 0141 339 8855
Office: 4652
Lab: 6644.
Pager: 07625 702883

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