Overview

Running an immunohistochemistry service at scale depends on predictable specimen flow and reliable supply, and the PD-L1 28-8 assay is a common choice for that purpose. As a validated IHC clone, 28-8 delivers a reproducible Tumor Proportion Score that many institutions use for immunotherapy decision support. Planning the sample pathway well keeps results on schedule.

How It Works

Tissue sections are stained with the 28-8 antibody using a validated automated platform, after which pathologists quantify the percentage of tumor cells with membrane staining. The resulting TPS is reported with the assay name and clone so the value can be interpreted against the correct threshold. Standardized reagents and controlled staining conditions keep scores consistent between runs.

Indications

The 28-8 assay is requested for patients being assessed for PD-1 pathway inhibition where this clone is the approved companion test. It is frequently used in thoracic oncology and in other tumor types with defined PD-L1 scoring labels. The output supports discussions about likely benefit from immune-based regimens.

Specimen & Reporting

A single FFPE block with adequate tumor content is sufficient, and unstained slides should be cut close to the time of submission. Reports return within roughly 5–7 working days and document the clone, platform, and TPS. Laboratories advise on slide count to avoid insufficient-material repeats.

Storage & Sourcing

Unstained slides are best shipped with desiccant at ambient temperature and scored promptly to preserve antigen integrity. For hospital networks and distributors, batch submission improves instrument utilization and lowers per-test cost. Give Life Time International maintains reagent stock and scheduling capacity so recurring orders are fulfilled without delay. Pre-analytical consistency such as uniform fixation time and section thickness improves stain reliability, and a documented cold chain for transported slides protects result quality across distant collection sites.

FAQ

Q: How many unstained slides should be sent for one 28-8 test? Most laboratories ask for 3–5 unstained sections on positively charged slides, with extra slides held in reserve if tumor content is low.

Q: What is the typical turnaround for a batched order? Single cases return in about a week; consolidated batches are scheduled to keep institutional throughput steady and predictable.

Q: Can 28-8 and 22C3 be compared directly? They are separate clones with separate approved thresholds, so scores should not be interchanged between companion-diagnostic contexts.

Q: How should slides be stored before shipment? Keep them at room temperature with desiccant, away from humidity and direct light, and ship within a short window before staining.