Immunohistochemistry Experiment (IHC) Protocol

critical

False-Positive Signal from Endogenous Enzyme Activity

High background signal observed when using enzyme-conjugated antibodies (HRP or AP), caused by endogenous alkaline phosphatase or peroxidase activity in tissue generating false-positive results.

💡 4 · ✓ 4

critical

Mouse-on-Mouse Cross-Reactivity in Tissue Staining

High background when using mouse primary antibodies on mouse tissue, caused by secondary antibody binding to endogenous mouse immunoglobulins and Fc receptors rather than only the primary antibody.

💡 4 · ✓ 4

severe

Tissue detachment / sections fall off the slide

Tissue falls off during staining; sections become broken or missing; results cannot be interpreted.

💡 4 · ✓ 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.

💡 4 · ✓ 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.

💡 4 · ✓ 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.

💡 4 · ✓ 5

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.

💡 3 · ✓ 3

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.

💡 4 · ✓ 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.

💡 4 · ✓ 4

moderate

Nuclear protein not detected due to insufficient permeabilization

No staining observed when targeting nuclear proteins. Antibody cannot access nuclear compartment despite proper antibody concentration and incubation time.

💡 3 · ✓ 4

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.

💡 3 · ✓ 3

moderate

High Background Staining in IHC

Excessive background signal obscuring specific staining. Non-specific binding observed throughout tissue sections, making interpretation difficult.

💡 5 · ✓ 5

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.

💡 3 · ✓ 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.

💡 4 · ✓ 4

moderate

Loss of membrane protein staining after permeabilization

No staining is detected when targeting membrane proteins in IHC. Signal is absent despite antibody validation, suggesting structural damage to membrane epitopes.

💡 3 · ✓ 4