(802) Multiplex Made Practical: An Educational Workflow Using Directly Conjugated Primary Antibodies

Introduction/Rationale: Spatial biology multiplex panels built from directly conjugated primary antibodies accelerate staining workflows and improve quantification accuracy of immunomarker expression by eliminating amplification bias. These advantages allow scientists to interrogate complex tissues with greater depth and precision. Here, we outline how to create and optimize primary antibody panels to characterize immune and structural features in healthy and malignant colon tissues.

Methods: Using a practical framework of steps and considerations that we will highlight in detail, we designed a panel comprising directly labeled antibodies to podoplanin, CD4, FoxP3, Ki67, CD8, CD68, PD 1, and CD3. CD3 was conjugated in-house using an antibody labeling kit, and we will describe the optimization of this procedure. We describe an effective method to combat autofluorescence using a combination of white light photobleaching + H2O2 and highlight ways to achieve superior unmixing performance using EVOS S1000.

Results: Immune cells comprised only about 10% of total cells in both samples, with tumors showing a marked increase in macrophages and a dramatic rise in proliferating Tregs, both associated with tumor progression and poorer outcomes. In the adenocarcinoma sample, we identified a tertiary lymphoid structure enriched primarily in cytotoxic and helper T cells, suggesting a potentially beneficial anti-tumor immune niche. Overall, these findings highlight how high-plex imaging enables detailed characterization of immune cell composition and spatial organization within colorectal tumors.

Conclusion: These findings show that directly conjugated multiplex panels offer a robust, scalable way to resolve complex tissue features while providing workflows that generate high-quality spatial data to accelerate biological insight and discovery. All reagents are intended for Research Use Only (RUO). Not for use in diagnostic procedures.