Our scientists are at the bench daily to produce and validate our antibodies, so they have hands-on experience and knowledge of each antibody’s performance.
The immune system employs a series of checkpoints to protect normal, healthy tissue from an immune response. These consist of receptors on the surface of activated T cells and their corresponding ligands on the surface of antigen presenting cells. A key immune checkpoint is triggered when PD-1 (programmed cell death protein 1) engages its ligand PD-L1. As a result of this interaction, T cell activation is attenuated and an active immune response is prevented(1).
This mechanism is often co-opted by tumors. PD-L1 is upregulated in several tumor types and contributes to the malignancy of these cancers by interacting with PD-1 and inhibiting T cell activation. In this way, the tumors avoid detection and destruction by the immune system(1-3). Accordingly, PD-1 and PD-L1 have garnered much attention for their roles in tumor immunology and as immune-based therapeutic targets(4,5).
CST PD-L1 product comparison for IHC-P analysis
|Product Name||PD-L1 (E1L3N®) XP® Rabbit mAb #13684||PD-L1 (405.9A11) Mouse mAb #29122||PD-L1 (Extracellular Domain Specific) (E1J2J) Rabbit mAb #15165|
|Antibody host species||Rabbit||Mouse||Rabbit|
|IHC analysis of paraffin-embedded human placenta|
|Recommended usage for IHC||Preferred clone based on sensitivity||Use when multiplexing with rabbit antibodies||Use for studying the extracellular domain of PD-L1|
Recognizes PD-L1 and does not cross-react with other B7 family members
Western blot analysis of lysates from:
- COS cells transfected with PD-L2
- COS cells mock transfected
- KARPAS-299 cells
- SUP-M2 cells
Demonstrates consistent, reliable results in immunohistochemistry, flow cytometry, western blotting and immunoprecipitation.
Flow cytometric analysis of untreated SUP-M2 cells using PDL1 (E1L3N®) XP® Rabbit mAb #13864 (blue) compared to concentration matched Rabbit (DA1E) mAb IgG XP® Isotype Control #3900 (red). Anti-rabbit IgG (H+L), F(ab')2 Fragment (Alexa Fluor® 647 Conjugate) #4414 was used as a secondary antibody.
KARPAS-299 and PC-3 Cell Staining
|CST PD-L1 (E1L3N®) XP® Rabbit mAb #13684 1:200||Company 1 Rabbit mAb 1:8000||Company 2 Mouse mAb 1:50|
|Strong, membrane associated staining||Weaker membrane staining than #13684||No membrane staining|
|No staining||Diffuse, Non-specific staining||Diffuse, Non-specific staining|
IHC analysis demonstrates that CST PD-L1 (E1L3N®) XP® Rabbit mAb #13684 at 1:200 gives a strong signal in KARPAS-299, which are known to be PD-L1 high expressing cells, and no staining in PC-3 cells. In contrast, Company 1 Rabbit mAb and Company 2 Mouse mAb stain both KARPAS-299 and PC-3 cells meaning that they are not specific for PD-L1.
Lung and Breast Carcinoma
|CST PD-L1 (E1L3N®) XP® Rabbit mAb #13684 1:200||Company 1 Rabbit mAb 1:8000|
|Predominantly membrane staining in lung carcinoma and no staining in stromal cells.||Staining in cytoplasm and membrane in both lung carcinoma and stromal cells.|
|No staining in PD-L1 negative breast carcinoma.||Non-specific nuclear and cytoplasmic staining in the PD-L1 negative breast carcinoma.|
In IHC analysis of human lung and breast carcinoma CST PD-L1 (E1L3N®) XP® Rabbit mAb #13684 demonstrates appropriate staining in lung carcinoma with no staining in surrounding stromal cells, and no staining in breast carcinoma. Company 1 Rabbit mAb, however, demonstrates staining in both lung carcinoma and surrounding stromal cells, and inappropriate staining in breast carcinoma. This antibody is detecting a protein that is not PD-L1.
Western blot analysis using CST PD-L1 (E1L3N®) XP® Rabbit mAb #13684 results in detection of a band at the appropriate molecular weight for PD-L1 in KARPAS-299 and SUP-M2 cells, which are known to have high PD-L1 expression, and no protein in A549 and PC-3, cells demonstrating that #13684 is specific for PD-L1. At the dilution recommended by the supplier, Company 1 Rabbit mAb produces multiple signals at various molecular weights in A549, PC-3, KARPAS-299, and SUP-M2 cells, demonstrating that this antibody is not specific for PD-L1.