Quality control comes in many forms in the IHC laboratory. Poor QC is unacceptable. It is important that you have a control for negative and positive staining (both reagent and tissue controls), as well as controls for the IHC system itself (manual or automated).
Controls are the key to successful IHC staining which assures quality and consistency, not only in the stain results, but also in the methodology. Controls provide guidance to identify problems, what caused the problems, and competency of the equipment/personnel performing the staining. Poor quality control can lead to poor quality results, so it is important to have an efficient quality management program in place for the IHC laboratory.