Antigen Unmasking

for Immunofluorescence and Immunohistochemistry workflows

Unlock Epitope Accessibility for Optimal Immunostaining

Formalin fixation is a standard method in immunohistochemistry (IHC) and immunofluorescence (IF) workflows to preserve tissue morphology. However, formalin induces cross-linking of proteins which can mask antigenic sites and hinder antibody binding.  

Antigen unmasking techniques restore epitope accessibility. The most common approach is heat-induced epitope retrieval (HIER) which involves heating tissue sections in specific buffer solutions to reverse formalin-induced cross-linking. 

Vector Laboratories' Antigen Unmasking Solutions

To achieve optimal staining on formalin-fixed tissues in IHC and IF workflows, Vector Laboratories offers two highly effective antigen unmasking solutions, each supplied as a 100x concentrated stock for convenience and reproducibility.

When used in combination with high-temperature treatment, these solutions efficiently reverse formalin-induced cross-linking, exposing antigenic sites for improved antibody binding and enhanced staining intensity. The figure below demonstrates how IHC staining is enhanced by using Vector’s Tris-Based Antigen Unmasking Solutions (H-3301-250).

Antigen Retrieval Figure1A
Antigen Retrieval Figure1B
Figure 1. Lymph Node tissue section without (left panel) and with (right panel) Tris-based Antigen Unmasking Solution. Tissue is stained using anti-Cyclin D1 rabbit monoclonal antibody, ImmPRESS® Anti-Rabbit IgG Kit, DAB (brown) substrate, and Hematoxylin QS (blue) counterstain.

Two Formulations for Broad Antigen Coverage:

Vector’s antigen unmasking solutions are available in two formulations to address most experimental design needs.

Antigen Unmasking Solution, Citrate-Based (H-3300-250)
  • pH: ~6.0
  • Ideal for most common antigen retrieval applications
  • Provides gentle but effective unmasking
  • Compatible with a wide range of primary antibodies
Antigen Unmasking Solution, Tris-Based (H-3301-250)
  • pH: ~9.0–10.5
  • Designed for antigens requiring alkaline conditions
  • Provides gentle but effective unmasking
  • Compatible with a wide range of primary antibodies

Why Choose Vector Laboratories' Antigen Unmasking Reagents?

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Convenient

Supplied as 100x concentrates allowing easy dilution for specific workflow needs.

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Reproducible Results

Standardized formulations eliminate batch-to-batch variability, ensuring consistency across experiments. 

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Broad Compatibility

Two formulation options cover the majority of primary antibody retrieval requirements.

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Seamless Integration

Designed to work efficiently with Vector’s IHC and IF detection systems.

Antigen Unmasking Technical and Educational Resources

For more information about antigen unmasking and how Vector products can streamline this step in your IHC and IF workflows, explore our resources.

Staining Sample Preparation Guide

Learn more about sample preparation, including antigen unmasking, and improve your staining with this guide.
Unmasking Epitopes Using Antigen Unmasking for Formalin-Fixed Tissue Staining
This article details considerations and troubleshooting for antigen retrieval in formalin-fixed tissues.