Unlocking the Tumor Microenvironment: Innovations in Multiplex Immunohistochemistry

Area of Science:

• Immunology
• Oncology
• Pathology

Background:

• Immune cell infiltration in tumors is crucial for cancer growth and treatment response.
• Understanding the spatial distribution of immune cells within the tumor microenvironment is vital.

Purpose of the Study:

• To demonstrate a feasible multiplex immunohistochemistry method for identifying immune cell markers in breast cancer.
• To characterize the infiltration patterns of B-cells, T-cells, and macrophages in relation to tumor compartments and tertiary lymphoid structures.

Main Methods:

• Utilized standard immunohistochemistry with novel chromogens for multiplex staining.
• Employed antibodies against CD20 (B-cells), CD3 (T-cells), CD163 (macrophages), cytokeratin (tumor identification), and Ki67 (proliferation index).
• Visual examination was used to differentiate up to five markers.

Main Results:

• Significant immune cell infiltration was observed surrounding and within breast tumors.
• B-cells, T-cells, and macrophages were abundant at the tumor periphery, often near tertiary lymphoid structures.
• B-cells were reduced within the tumor interior, while T-cells and macrophages showed abundant infiltration.

Conclusions:

• The developed multiplex staining method is feasible for visualizing immune infiltrates in breast cancer.
• Distinct patterns of immune cell infiltration exist, with differential distribution of B-cells, T-cells, and macrophages within and around tumors.
• Simple visual analysis can suffice for differentiating multiple immune markers in complex tissue samples.