TF Positive/Negative Dual-Control FFPE Standard | CBPN0079

Ⅰ.Product Overview

TF (Tissue Factor), also known as Coagulation Factor III or CD142, is encoded by the F3 gene located on human chromosome 1. The F3 gene is approximately 12.4 kb in length and encodes a 295-amino-acid protein consisting of three major structural regions: an extracellular domain, a transmembrane domain, and a cytoplasmic domain.

Physiologically, TF serves as the key initiator of the extrinsic coagulation pathway. Following vascular or tissue injury, TF binds to activated coagulation factor VII (FVIIa) to form the TF–FVIIa complex, thereby initiating the coagulation cascade and promoting fibrin formation for hemostasis.

In oncology research, TF is aberrantly expressed in a variety of solid tumors, including cervical, breast, lung, prostate, and ovarian cancers, and has been associated with tumor invasion, metastasis, and poor clinical outcomes. TF has also emerged as an increasingly investigated antibody–drug conjugate (ADC) target.

The development of TF-targeted ADCs is relatively recent. Following the approval of Tivdak (tisotumab vedotin) and the clinical development of MRG004A, TF has attracted increasing attention from pharmaceutical companies and research institutions as a potential therapeutic target for advanced solid tumors.

Immunohistochemistry (IHC) is a key method for evaluating TF protein expression in tissue samples. However, IHC results can be significantly affected by antibody performance, antigen retrieval conditions, staining parameters, and overall assay workflow.

TF Positive/Negative Dual-Control FFPE Standard, CBPN0079, combines TF-positive and TF-negative tissue regions within a single paraffin block. It is specifically designed for TF-IHC antibody validation, assay quality control, and optimization of staining conditions.

By incorporating both positive and negative controls into the same FFPE block, CBPN0079 enables simultaneous assessment of assay sensitivity and specificity while minimizing experimental variability. The product is suitable for TF target research, antibody development, IHC assay development, and methodological validation in TF-targeted ADC research and companion diagnostic development.

Ⅱ.Product Specifications

Parameter	Specification	Description
Product No.	CBPN0079	Unique product identifier. Please provide this product number when requesting the corresponding COA or technical support.
Product Format	FFPE Paraffin Block	Formalin-fixed, paraffin-embedded (FFPE) tissue block, a standard sample format widely used in pathology and IHC applications.
Block Thickness	4 mm	The thickness of the paraffin block itself is 4 mm. For IHC, the block should be sectioned into standard 3–5 μm tissue sections. Cell content may vary between individual samples and batches without affecting the intended control function.
Validated Antibody	Tissue Factor Recombinant Rabbit mAb (S-893-34); Staidt, Cat. No. S0B0577	The FFPE standard has been validated by IHC using this antibody. The validated antibody and conditions may be used as a reference for experimental setup. The product can also be used to evaluate TF antibodies developed in-house or supplied by other manufacturers.
Intended Use	Research Use Only (RUO)	For research use only. Not intended for direct clinical diagnostic use.
Storage	−25°C to −15°C	Store the paraffin block under frozen conditions and avoid repeated freeze–thaw cycles. Prolonged storage at room temperature may result in antigen loss or tissue damage and may compromise control performance.
Shelf Life	36 months from the date of manufacture	Use within the specified shelf life. After sectioning, staining should be performed as soon as practicable.

Key Specification Notes

1.Storage Temperature

The product should be stored frozen at −25°C to −15°C. Long-term storage at 4°C or room temperature is not recommended. Improper storage may lead to degradation or loss of TF antigenicity, resulting in reduced staining intensity in positive regions and compromising the performance of the control.

2. Sectioning Requirements

The specified 4 mm thickness refers to the physical thickness of the paraffin block, not the thickness of the IHC section.

For IHC analysis, the FFPE block should be sectioned into thin tissue sections, typically 3–5 μm, and mounted onto positively charged or other suitable adhesion slides.

3. Tissue/Cell Content

The statement “cell content may vary” is a standard specification for tissue-based FFPE reference materials. Minor variations in tissue or cell composition may occur between manufacturing batches. The expected positive/negative expression characteristics are verified during batch release and are not expected to affect the intended control function.

4. Validated Antibody

CBPN0079 has been validated by IHC using Tissue Factor Recombinant Rabbit mAb (S-893-34), Cat. No. S0B0577.

The validated antibody and associated staining conditions can be used as a reference when establishing an IHC assay. When using other TF antibodies, users should independently optimize the relevant staining conditions.

Ⅲ.IHC Staining Reference

CBPN0079 is released following TF-IHC staining validation. The FFPE block contains both TF-positive and TF-negative tissue regions, providing an integrated positive/negative control within a single paraffin block.

1. Interpretation of the Positive Control Region

The positive tissue region is expected to exhibit clear and specific TF staining, with staining localized primarily to the cell membrane and/or cytoplasm, while nonspecific background staining in the surrounding tissue remains low.

The positive control region can be used to assess whether the overall IHC workflow is functioning properly, including antigen retrieval, primary antibody incubation, and chromogenic detection.

Normal positive staining: Indicates that the IHC workflow is capable of detecting the target TF antigen under the tested conditions.

Absent or markedly reduced positive staining: May indicate issues such as insufficient antigen retrieval, reduced antibody activity, inadequate antibody incubation, or other assay-related factors.

2. Interpretation of the Negative Control Region

The negative tissue region should show little to no specific TF staining, with only minimal background staining expected.

This region is used to assess the level of nonspecific staining within the IHC assay.

Prominent staining in the negative region: May indicate nonspecific antibody binding, insufficient blocking, excessive chromogenic development, or other assay-related issues. Such results should be carefully evaluated before interpreting experimental samples.

Clean negative region with adequate positive staining: Supports good assay specificity and appropriate IHC performance under the tested conditions.

3. Advantages of the Dual-Control Design

The positive and negative control tissues are incorporated into the same FFPE block and can be evaluated on the same tissue section. This ensures that sectioning, deparaffinization, antigen retrieval, antibody incubation, and chromogenic development are performed under the same experimental conditions.

Compared with separate positive and negative control blocks, the dual-control design minimizes variability caused by differences between tissue sections and experimental runs.

This format is particularly useful for:

• IHC assay optimization

• Antibody performance comparison

• Antibody screening

• Staining condition optimization

• Inter-batch assay consistency assessment

• Routine laboratory IHC quality control

Ⅳ.Key Applications

CBPN0079 can be used across a range of TF-related research and assay development applications, including:

1. TF-IHC Antibody Evaluation

Assessment and screening of TF-targeting antibodies for IHC applications.

2. IHC Assay Development and Optimization

Optimization of antigen retrieval conditions, antibody concentrations, incubation times, and other critical staining parameters.

3. TF-Targeted ADC Research

Development and methodological validation of TF-IHC assays supporting TF-targeted ADC research and companion diagnostic development.

4. Routine IHC Quality Control

Internal laboratory quality control and monitoring of IHC assay performance and workflow consistency.

5. TF-Related Oncology Research

Use as an experimental control for studies investigating TF expression in tumor tissues and TF-associated biological mechanisms.

Ⅴ.Handling and storage Recommendations

Minimize room-temperature exposure. After removing the paraffin block from frozen storage, proceed with sectioning as soon as practicable. Return the remaining block to −25°C to −15°C storage promptly after sectioning to minimize potential antigen loss.

Use appropriate adhesion slides. Positively charged or other suitable adhesive slides are recommended to reduce tissue detachment during heat-induced antigen retrieval and subsequent IHC procedures.

Research Use Only. This product is intended for research use only (RUO) and is not intended for clinical diagnosis.

COA Documentation. A Certificate of Analysis (COA) is provided for each product batch. Users are recommended to retain the corresponding COA for future reference. The batch-specific COA includes the IHC staining results used for product release and quality assessment.