Hello Histonetters!
I've been asked to work out CD4 staining on formalin-fixed, paraffin
embedded lymph node. Naturally, the first thing I did was to look at the
Histonet Archives. I have tried both the Novocasta and Serotec CD4
primaries, which are the same clone. HIER in the microwave with EDTA pH8
gives the strongest signal, but the staining looks "muddy" and the
background is high.  I have tried several different variations, including
avidin-biotin blocking, serum block, biotinylated-anti-mouse secondary,
etc., and still no improvement. Our lab uses a Ventana Biotech automated
stainer for routine IHC, and the ideal situation would utilize the
accompanying Ventana kit reagents, but I have also tried Vector reagents,
staining manualy and with our DAKO autostainer. 

Any suggestions? Anyone with a working protocol? 
Many thanks in advance, 

Rachel Stock, HTL(ASCP)
UMass Medical Center
Worcester, MA