Had success with murine paraffin sections using Carnoys (we left out the
chloroform), no retrieval needed.  Pharmingen has recipe for fixative
called zinc fixative, a formalin free fixation for cell surface markers,
which gives fairly good morphology, no retrieval, but you have to use Alk
Phos (endog peroxidase cannot be quenched after this nonformalin fix). Go
to www.pharmingen.com for recipe and how to fix.  Beware the tissues are
more friable with this fixation and you have to fix SMALL pieces of
tissues.   

You may want to try some type of enzyme digestion to retrieve, trypsin,
proeteinase K, pronase if you have formalin fixed the tissue rather than a
buffer retrieval.  Murine CD markers often hate NBF much to mouse people's
dismay, and frozens are THE only recourse. Pharmingen does not recommend
FFPE murine tissue for CD11b, M1/70 clone.  

My morphology improved greatly on frozen sections after air drying
overnight (I store slides over blue silica gel to insure total drying), fix
with acetone 75%/absolute ethanol 25% 5 min RT, rinse immediately with
buffer X 3, proceed with staining.  With CD11b, it works beautifully, as it
does with CD4, 8 etc. I prefer glucose oxidase endog peroxidase blocking.  


Gayle Callis
MT,HT,HTL(ASCP)
Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
Bozeman MT 59717-3610

406 994-6367
404 994-4303 (FAX)