Home โ€บ Microscopy & Imaging โ€บ Immunohistochemistry Protocol for Paraffin embedded Tissue Sections
Steps
  1. 1 Sample Preparation and Deparaffinization/Rehydration 01:39
  2. 2 Antigen Unmasking 02:45
  3. 3 Chromogenic Staining 03:48
Microscopy & Imaging Cell Signaling Technology

Immunohistochemistry Protocol for Paraffin embedded Tissue Sections

Protocol

IHC on paraffin-embedded tissue sections: deparaffinization, antigen retrieval, peroxidase blocking, primary and secondary antibody incubation, DAB detection, and counterstaining.

Difficulty
intermediate
Total time
6-8 hours (or overnight)
Biosafety
BSL-1

Steps

1
Sample Preparation and Deparaffinization/Rehydration

Bake slides at 60 C for 1 hour to melt paraffin. Pass slides through xylene (3 x 5 min) to remove paraffin, then graded ethanol (100%, 95%, 70%) and water to rehydrate the tissue for downstream staining.

โ–ถ 01:39
2
Antigen Unmasking

Restore epitopes masked by formalin fixation: heat slides in citrate buffer (pH 6) or EDTA buffer (pH 9) at near-boiling for 10-20 min using a steamer or pressure cooker; cool slowly to room temperature.

โ–ถ 02:45
3
Chromogenic Staining

Block endogenous peroxidase (3% H2O2, 10 min) and non-specific binding (normal serum). Apply primary antibody overnight at 4 C; wash with TBST; apply HRP-conjugated secondary antibody (30 min); develop with DAB substrate until brown signal appears. Counterstain nuclei with hematoxylin, dehydrate, and mount.

โ–ถ 03:48

๐Ÿšจ Failure Case Library (29) + Submit your own case

critical
False negative โ€” no staining at all
Even the positive control shows no staining; expected positive regions are completely blank; the experiment failed.
๐Ÿ’ก 4 ยท โœ“ 4
critical
Complete Absence of IHC Staining
Complete lack of staining observed in immunohistochemistry experiment despite using validated antibody. Tissue sections appear negative even when positive control should show signal.
๐Ÿ’ก 6 ยท โœ“ 6
severe
Tissue detachment / sections fall off the slide
Tissue falls off during staining; sections become broken or missing; results cannot be interpreted.
๐Ÿ’ก 4 ยท โœ“ 4
severe
Abnormal nuclear staining (wrong subcellular localization)
Cell nuclei show strong staining when they shouldn't, or expected positive nuclei show no staining; nuclear/cytoplasmic localization is wrong.
๐Ÿ’ก 4 ยท โœ“ 4
severe
High Background from Insufficient Non-Specific Blocking
Diffuse background staining observed throughout tissue sections in IHC experiments, indicating inadequate blocking of non-specific antibody binding sites.
๐Ÿ’ก 4 ยท โœ“ 4
severe
Over-Amplified Signal with Biotin-Based Detection Systems
Excessive background staining when using amplification techniques or biotin-based detection, either from high signal amplification or endogenous biotin binding to streptavidin/avidin.
๐Ÿ’ก 4 ยท โœ“ 4
severe
High Background from Excessive Antibody Concentrations
Elevated background staining throughout tissue sections due to excessively high concentrations of primary or secondary antibodies leading to non-specific binding.
๐Ÿ’ก 4 ยท โœ“ 5
severe
Complete absence of IHC signal due to reagent degradation
No staining is observed in immunohistochemistry despite proper protocol execution. Previously validated antibodies or detection kits fail to produce any signal.
๐Ÿ’ก 4 ยท โœ“ 6
severe
Incorrect Antibody Diluent Selection
Suboptimal signal intensity or background issues despite correct antibody concentration. Different antibodies show dramatically different performance in TBST/5% NGS versus SignalStain Antibody Diluent.
๐Ÿ’ก 3 ยท โœ“ 3
severe
Mouse-on-Mouse (MOM) Background
High background staining when using mouse primary antibody on mouse tissue. Secondary antibody binds endogenous mouse IgG throughout the tissue, creating non-specific signal.
๐Ÿ’ก 3 ยท โœ“ 4
severe
Strong positive background / non-specific staining
Whole slide appears brown/diffuse stained; negative control also shows signal; impossible to distinguish true positive signal.
๐Ÿ’ก 5 ยท โœ“ 5
severe
Weak staining / signal too faint
Positive regions show very pale staining; barely distinguishable from negative control; signal appears dotted or discontinuous.
๐Ÿ’ก 5 ยท โœ“ 5
severe
Residual Reagent Background from Inadequate Washing
Elevated background signal caused by residual fixative or unbound antibodies remaining on tissue sections between procedural steps, producing false-positive staining.
๐Ÿ’ก 5 ยท โœ“ 5
severe
Weak or Suboptimal IHC Staining Intensity
Staining signal is present but significantly weaker than expected, with poor contrast between positive cells and background, making interpretation difficult.
๐Ÿ’ก 5 ยท โœ“ 5
severe
Antigen Retrieval Method Not Optimized for Target
Staining results are inconsistent or suboptimal despite correct antibody and detection system, with signal strength varying significantly based on retrieval method used.
๐Ÿ’ก 4 ยท โœ“ 4
severe
Inadequate Detection System Sensitivity
Weak signal or no staining despite proper primary antibody performance. Standard HRP-conjugated secondary antibodies fail to provide sufficient signal amplification.
๐Ÿ’ก 4 ยท โœ“ 4
severe
Suboptimal Antigen Retrieval Method Selection
Weak or absent staining despite proper antibody concentration and incubation. Clear performance differences observed when comparing different antigen retrieval heating methods.
๐Ÿ’ก 4 ยท โœ“ 4
moderate
Non-Specific Binding from Elevated Incubation Temperature
Increased background staining when primary antibody incubation is performed at room temperature, as higher temperatures promote non-specific antibody-tissue interactions.
๐Ÿ’ก 4 ยท โœ“ 4
moderate
Edge Artifacts from Tissue Section Drying
Higher background staining concentrated at the edges of tissue sections compared to the center, indicating tissue dehydration during the staining procedure.
๐Ÿ’ก 4 ยท โœ“ 5
moderate
FFPE tissue shows no staining from incomplete deparaffinization
Paraffin-embedded tissue sections show no immunostaining. Residual paraffin creates a physical barrier preventing antibody access to tissue antigens.
๐Ÿ’ก 3 ยท โœ“ 4
moderate
Weak or absent signal from inadequate antibody concentration or incubation
No detectable staining despite proper protocol execution. Insufficient antibody-antigen binding due to suboptimal concentration or incubation conditions.
๐Ÿ’ก 4 ยท โœ“ 5
moderate
Spotty or Uneven Background Staining Pattern
Staining pattern shows irregular, patchy, or spotty background with uneven distribution across tissue sections, indicating technical artifacts rather than biological variation.
๐Ÿ’ก 3 ยท โœ“ 3
moderate
High Background Staining in IHC
Excessive background signal obscuring specific staining. Non-specific binding observed throughout tissue sections, making interpretation difficult.
๐Ÿ’ก 5 ยท โœ“ 5
moderate
Incorrect Antibody Diluent Selection
Staining quality is significantly reduced or inconsistent when using generic diluent instead of product-specific recommended diluent, as different antibodies perform optimally in different buffer compositions.
๐Ÿ’ก 3 ยท โœ“ 4
moderate
Insufficient Detection System Sensitivity
Signal is weak or undetectable despite correct antibody and protocol, particularly for low-abundance targets, indicating that the detection system lacks sufficient signal amplification.
๐Ÿ’ก 3 ยท โœ“ 4
moderate
Inadequate Washing Steps Causing Poor Contrast
High background persists with poor contrast between positive signal and background despite other optimization steps, making interpretation difficult.
๐Ÿ’ก 4 ยท โœ“ 4
moderate
Endogenous Biotin Interference
High background staining specifically in kidney, liver, or other biotin-rich tissues when using biotin-based detection. Background not resolved by standard blocking procedures.
๐Ÿ’ก 3 ยท โœ“ 3
moderate
Edge effect / uneven staining across the slide
Slide edges show darker staining than center, or one half stains more than the other; reproducibility between fields is poor.
๐Ÿ’ก 4 ยท โœ“ 4
moderate
Suboptimal Primary Antibody Incubation
Inconsistent or weak staining results despite following protocol. Staining intensity varies between experiments using same antibody lot and tissue type.
๐Ÿ’ก 3 ยท โœ“ 3
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