[Histonet] Weak progesterone staining, 1A6, Ventana

[Jennifer Englin]

Has anyone noticed any weakening in their progesterone staining with the 1A6 antibody from Ventana?  We have been getting good results with this antibody and our standard procedure until recently, when it has become very weak.  Fixation has not changed much, although we have tried to regulate this more tightly.  Our procedure is the same for both the Nexes and ES:
Antigen retrieval- Dako Target:  100 degrees C in a steamer for 20 min and cool  down 20 min

Our protocol is:
Antibody (predilute) 32 min
Amplifier
A/B Block
i-view detection kit

We have tried retrieval with several different times- zero, 10 min, 20 min, and 40 min.  40 min works best but is still very weak.  Any suggestions would be very welcome.

Jennifer Englin, HT(ASCP),PA
Rice Memorial Hospital
Willmar, MN