Re: [Histonet] Cell Block preparation (lengthy)

From:"Bryan Hewlett"


I have compared a number of methods for preparing cell blocks for IHC and 
have the following comment;

Overall, I much prefer the plasma/thrombin method.
Primarily because freshly harvested cells can be collected in plasma, 
transported, aliquoted and the cell concentration easily adjusted, prior to 
addition of thrombin.
Furthermore, unfixed cells are now completely surrounded by the same 
proteinaceous intercellular matrix found in all solid tissues.
This proteinaceous matrix is a necessary and crucial component of all 
fixation reactions in tissue and actively participates in the fixation 
To my way of thinking, cell blocks produced this way more closely mimic 
solid tissues for IHC control purposes!
Once clotted (15 mins including retraction) the cell blocks can be optimally 
fixed and processed.

We have used this method for preparing numerous cell blocks for IHC.
The only background staining seen is a specific background, due to secondary 
reagents being insufficiently absorbed against human Ig's, this is easily 
corrected as necessary.
One caveat, this type of specific background will interfere with 
interpretation of staining for Human Ig's, Kappa/Lambda light chains and 
particularly if agonal imbibition by dying cells occurs.


----- Original Message ----- 
From: "Houston, Ronald" 
Sent: Tuesday, May 29, 2007 4:15 PM
Subject: [Histonet] Cell Block preparation

Would anyone care to comment on the pros and cons of preparing cell
blocks using the Plamsa/thrombin technique and the Agar method which is
more prominent in the European field?

I am particularly interested in the prevalence of background staining in
ICC. Does the use of plasma interfere with interpretation of the
staining results? I know there have been reports of extraneous tissue
being found in cell blocks coming from a commercially prepared clotting



Ronnie Houston, MS, HT(ASCP)QIHC

Anatomic Pathology Manager

Columbus Children's Hospital

700 Children's Drive

Columbus, OH 43205

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