Knowledge Base › Troubleshooting Atlas › IHC
Positive control fails in IHC
What it looks like
The positive control shows weak or no staining in IHC assays. The expected strong staining is absent or diminished.
Where it usually appears: Typically appears in the positive control tissue sections during immunohistochemistry staining procedures.
Likely causes
- Expired or improperly stored antibodies
- Inadequate antigen retrieval
- Incorrect dilution of primary antibody
- Insufficient incubation time or temperature
- Improper fixation of tissue samples
Immediate checks
- Verify antibody expiration date
- Check storage conditions of antibodies
- Confirm antigen retrieval method used
Corrective action
- Re-run the IHC using fresh antibodies
- Adjust antigen retrieval parameters
- Increase incubation time for primary antibody
Preventive action
- Regularly check and replace expired reagents
- Establish proper fixation protocols
- Maintain a log of antibody storage conditions
This atlas is for educational purposes for laboratory professionals. It does not replace your institutional SOPs, manufacturer instructions, validated protocols or pathologist judgment. Adapt any action to your laboratory and equipment.
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