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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
Clone E1L3N® 405.9A11 E1J2J
Epitope Intracellular Intracellular Extracellular
Antibody host species Rabbit Mouse Rabbit
IHC analysis of paraffin-embedded human placenta IHC Placenta for PD-L1 (E1L3N) IHC Placenta for PD-L1 (405.9A11) IHC Placenta for PD-L1 (Extracellular Domain Specific)
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

PD-L1 Western Blotting

Western blot analysis of lysates from:

  1. COS cells transfected with PD-L2
  2. COS cells mock transfected
  3. KARPAS-299 cells
  4. SUP-M2 cells

Demonstrates consistent, reliable results in immunohistochemistry, flow cytometry, western blotting and immunoprecipitation.

PD-LI Flow Cytometry

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.