Siglecs: targets for immune regulation and cancer therapy

sialic acid-binding immunoglobulin-type lectins

Siglecs (sialic acid-binding immunoglobulin-type lectins) are receptors predominantly located on the surface of hematopoietic cells. Recent publications highlight the important roles Siglecs play in tumor immunosurveillance making them attractive anti-cancer drug targets. Inhibitory receptors Siglec-7 and Siglec-9 are expressed on NK cells and recognize tumor-associated sialosides (1,2). Also, Siglec-15 (Catalog # 9227-SL) was identified as an immune suppressor by engaging an unknown receptor on T cells. Similar to PD-L1/PD-1 immune checkpoint blockade, Siglec-15 may be a potential target for cancer immunotherapy (3).

Siglecs interact with an array of linkage-specific sialic acids on a glycan structure expressed on host cells, as well as pathogens. So far, there are 15 different human and 9 murine Siglecs. Each type of Siglec generally recognizes a particular set of sialylated glycan containing differently linked sialic acid molecules (4,5). On the cytoplasmic side, most Siglecs have immune receptor tyrosine-based inhibition motifs (ITIM), which initiate signaling cascades resulting in downregulation of proinflammatory responses.

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Protein Species Source Tag Catalog # Activity
Siglec-1/CD169 Human NS0 His 5197-SL Supports RBC adhesion
Mouse NS0 Fc 5610-SL
Siglec-2/CD22 Human NS0 Fc 1968-SL Supports RBC adhesion
Human CHO Fc, Avi-tag AVI1968
Human NS0 Fc, Alexa Fluor® 488 AFG1968 Binds anti-Siglec-2 / CD22 monoclonal antibody conjugated beads
Human NS0 Fc, Alexa Fluor® 647 AFR1968
Human NS0 Fc, Atto 488 ATJ1968
Human NS0 Fc, Atto 647N ATM1968
Human CHO His 10191-SL Supports RBC adhesion
Human CHO His, Avi-tag AVI10191
Mouse NS0 Fc 2296-SL
Cynomolgus Monkey HEK293 Fc 10031-SL
Cynomolgus Monkey HEK293 His 9864-SL
Rat CHO Fc 10572-SL
Rat CHO His 10571-SL
Siglec-3/CD33 Human NS0 Fc 1137-SL Supports RBC adhesion
Human CHO His, Avi-tag AVI1137
Human NS0 Fc, Alexa Fluor® 488 AFG1137 Binds anti-Siglec-3 / CD33 monoclonal antibody conjugated beads
Human NS0 Fc, Alexa Fluor® 647 AFR1137
Human NS0 Fc, Atto 488 ATJ1137
Human NS0 Fc, Atto 647N ATM1137
Human CHO His 10375-SL Supports RBC adhesion
Human HEK293 Fc, Avi-tag AVI10467
Mouse NS0 Fc 10102-SL Binds Siglec H (Caalog # 10264-SH)
Cynomolgus Monkey CHO Fc 10885-SL Binds Galectin-3BP/MAC-2BP (Catalog # 2226-GAB)
Cynomolgus Monkey CHO His 11217-SL  
Siglec-4a/MAG Human HEK293 Fc 8940-MG Inhibits neurite outgrowth of E13 chick embryonic DRG neurons
Mouse NS0 Fc 8580-MG
Rat NS0 Fc 538-MG
Siglec-5/CD170 Human NS0 Fc 1072-SL Supports RBC adhesion
Siglec-6/CD327 Human CHO Fc 2859-SL Binds biotinylated Neu5Ac alpha 2-6GalNAc alpha
Siglec-7/CD328 Human NS0 Fc 1138-SL Supports RBC adhesion
Siglec-8 Human NS0 Fc 9045-SL Binds biotinylated Sialyl Lewis X
Siglec-9 Human NS0 Fc 1139-SL Supports RBC adhesion
Cynomolgus Monkey HEK293 Fc 11242-SL
Siglec-10 Human NS0 Fc 2130-SL Binds biotinylated 6’-Sialyllactose-Polyacrylamide
Human CHO Fc, Avi-tag AVI2130 Binds CD52 (Catalog # 9116-CD)
Siglec-11 Human CHO Fc 3258-SL Binds biotinylated (Neu5Aca2-8)2-Polyacrylamide
Siglec-14 Human NS0 Fc 4905-SL Supports RBC adhesion
Siglec-15 Human CHO Fc 9227-SL Inhibits anti-CD3 induced IFN-gamma secretion by T cells
Human CHO His 10698-SL
Mouse NS0 Fc 10101-SL Inhibits anti-CD3 induced IL-2 secretion by T cells
Mouse NS0 His 10288-SL
Siglec-E Mouse NS0 Fc 5806-SL Binds biotinylated Neu5Ac alpha 2-6GalNAc alpha -Polyacrylamide
Siglec-F Mouse NS0 Fc 1706-SF Supports RBC adhesion
Mouse NS0 His 10171-SF 
Siglec-G Mouse NS0 Fc 10103-SL Binds biotinylated 6'-Sialylactose-PAA
Siglec-H Mouse NS0 Fc 10264-SH Binds Siglec-3 (Catalog # 10102-SL)
Alexa Fluor® is a registered trademark of Molecular Probes, Inc., Eugene, OR.
Recombinant Cynomolgus Monkey Siglec 2/CD22 Fc Chimera Protein
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Recombinant Human Siglec-15 Fc Chimera protein
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Recombinant Mouse Siglec F His-tag protein
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Recombinant Cynomolgus Monkey Siglec‑2/CD22 Fc Chimera (Catalog # 10031-SL) supports the adhesion of human red blood cells. The ED50 for this effect is 0.07-0.42 ug/mL. Recombinant Human Siglec-15 Fc Chimera (Catalog # 9227-SL) inhibits anti-CD3 antibody induced IFN-gamma secretion by human T cells. The ED50 for this effect is 1-10 μg/mL. 2 μg/lane of Recombinant Mouse Siglec‑F His-tag (Catalog # 10171-SF) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing bands at 59-68 kDa.

References:

1. Jandus, C. et al. (2014) J. Clin. Investig. 124:1810.

2. Stanczak, M.A. et al. (2018) J. Clin. Investig. 128:4912.

3. Wang, J. et al. (2019) Nat. Med. 25:656.

4. Bornhöfft, K.F. et al. (2018) Dev. Comp. Immunol. 86:219.

5. Zhou, J.Y. et al. (2018) Trends Immunol. 39:523.

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