Bioactive Proteins: Immune Checkpoint

Regulators of the immune checkpoint represent some of the most promising targets for immunotherapy. R&D Systems offers the widest selection of checkpoint proteins, all assessed for bioactivity and held to rigorous specifications that must be matched for each lot of protein made. The proteins include a selection of different tags and species, including Cynomolgus, allowing for maximum experimental flexibility. Our selection ranges from traditional targets such as PD-L1 and CTLA4, to next generation targets such as the Butyrophilins and LILRA/B Receptors. Custom options are available for new proteins, tags, species, and more.

Biotinylated Proteins   Expanding selection of Recombinant Cynomolgus Proteins
B7-related Butyrophilins   Amigo Proteins

B7/CD28 Family

This group contains some of the most targeted checkpoint proteins, including PD-1, PD-L1, and CTLA4.

LILRA/B Receptors

Inhibitory leukocyte immunoglobulin-like receptors are increasingly recognized for putative roles in immune checkpoint and tumor promoters.



Butyrophilins have similar structure to the B7 family and are promising new checkpoint targets.

Nectin and Nectin-like Ligand/Receptors

Including TIGIT and CD155/PVR, modulators of T Cell and NK cell activity and important immunotherapy targets.


Fc Receptors

Fc receptors bind antibodies where they regulate the immune response and the antibody pharmacokinetics.

TIM Family/Galectin

Use our immunoassays and kits to measure cytokine secretion, proliferation, and cytotoxicity to ensure T cells are functioning as expected.


Kynurenine Pathway

Enzymes of the Kynurenine pathway include Tryptophan Hydroxylases, Kynurenine 3-Monooxygenase (KMO), Indoleamine 2,3 dioxygenases (IDO), Kynurenine Aminotransferase 1 (KAT1), and KAT2 (alpha-Aminoadipate Aminotransferase). Known for immunosuppressive function, the enzymes are checkpoint targets.

SLAM Family

Expressed by a range of immune cell types, most members of the SLAM family can interact homotypically and may be immune activators or suppressors.


LAIR Family

LAIR1 is a collagen-binding partner and a suppressor of T cell proliferation and activation.

TNF Receptor Superfamily Co-signaling

A subset of this large family include immune checkpoint targets such CD40 , GITR, and HVEM.


VSIG Proteins

A subset of the V-set and Ig domain-containing (VSIG) proteins are being recognized for their association with immune checkpoint, including TIGIT and VSIG3, a novel Vista-interacting protein.


Proteins including LAG-3, DPPIV, certain Integrins, and others are current targets of immune checkpoint research.