All factors related to each testing phase of specimen processing in the pathology laboratory may affect IHC staining.
Critical variables that affect staining results include:
- Temperature
- pH
- Ionic conditions
- Titer of antibody concentration
- Number of epitope sites per cell
- Duration of incubation
- Fixation and tissue processing
Table 1. Quality Control (QC) Factors by Test Phase.| Pre-Examination | Examination | Post-Examination |
| Fixation: Time, type, volume | Heating, dewax, pretreatments | Localization, Interpretation |
| Tissue: Type, dimension | Antigen retrieval | Positive-negative tissue controls: Cut-off values or scoring |
| Tissue processing complete | Primary AB, dilution, clone, time, temperature | Report elements (e.g., synoptic) |
| Decalcification: Type, time | Detection: Sensitivity, selectivity | FDA disclaimers |
| Section thickness, drying, storage | Controls | |
Note: Not a complete list.
