Human Siglec-2/CD22 LlaMABody^TM VHH Antibody

Catalog #: LMAB11048 Datasheet / COA / SDS

Recombinant Monoclonal Antibody. His-tagged VHH domain

Catalog #	Availability	Size / Price	Qty
LMAB11048-100
LMAB11048-SP

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Human Siglec-2/CD22 LlaMABody^TM VHH Antibody Summary

Species Reactivity

Human

Specificity

Detects human Siglec-2/CD22 in direct ELISAs.

Source

Recombinant Monoclonal Llama V_HH domain Clone # L007.2.5LL

Purification

His-tag purified from cell culture supernatant

Immunogen

Chinese Hamster Ovary cell line CHO-derived human Siglec-2/CD22
Asp20-Arg687
Accession # CAA42006.1

Formulation

Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. *Small pack size (SP) is supplied either lyophilized or as a 0.2 µm filtered solution in PBS.

Label

Unconjugated

Applications

Recommended Concentration

Sample

Immunocytochemistry

8-25 µg/mL

Immersion fixed Daudi human Burkitt's lymphoma cell line

Please Note: Optimal dilutions should be determined by each laboratory for each application. General Protocols are available in the Technical Information section on our website.

Scientific Data

Immunocytochemistry

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Siglec‑2/CD22 in Daudi Human Cell Line. Siglec‑2/CD22 was detected in immersion fixed Daudi human Burkitt's lymphoma cell line (positive staining) and THP‑1 human acute monocytic leukemia cell line (negative staining) using Llama Anti-Human Siglec‑2/CD22 Llamabody^TM VHH Monoclonal Antibody (Catalog # LMAB11048) at 8 µg/mL for 3 hours at room temperature. Cells were stained using an anti-Alpaca Alexa 594 antibody (red) and counterstained with DAPI (blue). Specific staining was localized to cell surface. Staining was performed using our protocol for Fluorescent ICC Staining of Non-adherent Cells.

Reconstitution Calculator

Preparation and Storage

Reconstitution

Reconstitute at 0.5 mg/mL in sterile PBS.

Shipping

Lyophilized product is shipped at ambient temperature. Liquid small pack size (-SP) is shipped with polar packs. Upon receipt, store immediately at the temperature recommended below.

Stability & Storage

Use a manual defrost freezer and avoid repeated freeze-thaw cycles.

12 months from date of receipt, -20 to -70 °C as supplied.
1 month, 2 to 8 °C under sterile conditions after reconstitution.
6 months, -20 to -70 °C under sterile conditions after reconstitution.

Background: Siglec-2/CD22

Siglecs are type I transmembrane proteins that belong to the immunoglobulin (Ig) superfamily and function as mammalian lectins (1). They are characterized by an extracellular domain consisting of various numbers of Ig domains with a conserved N-terminal V-set Ig ligand-binding domain. This binds species-specific sialic acid motifs on protein and lipid scaffolds to regulate intracellular signaling pathways (2). The cytoplasmic tail has signaling motifs, in most cases immunoreceptor tyrosine-based inhibitory motif (ITIM) (3). Human Siglec-2, also known as B cell antigen CD22 or B lymphocyte cell adhesion molecule (BL-CAM), is a B cell restricted glycoprotein that is expressed in the cytoplasm of progenitor B and pre B cells and on the surface of mature B cells. Two distinct human Siglec-2/CD22 cDNAs that arise from differential RNA processing of the same gene have been isolated. The predominant Siglec-2/CD22 beta encodes an 847 amino acid (aa) polypeptide with a hydrophobic signal peptide, an N-terminal Ig-like V type domain, six Ig-like C2 type domains, a transmembrane region and a cytoplasmic tail with 4 immunoreceptor tyrosine-based inhibition motifs (ITIMs) (4). The variant Siglec-2/CD22 alpha encodes a 647 aa polypeptide missing two Ig-like C2 type domains and has a truncated (23 aa) cytoplasmic tail (5). Mature human Siglec-2 beta consists of a 668 amino acid (aa) extracellular domain (ECD), a 19 aa transmembrane segment, and a 141 aa cytoplasmic domain. Within the ECD, human Siglec-2 shares 59% and 58% aa sequence identity with the mouse and rat Siglec-2, respectively. Siglec-2/CD22 is an adhesion molecule that preferentially binds alpha 2,6- linked sialic acid on the same (cis) or adjacent (trans) cells. Interaction of CD22 with trans ligands on opposing cells was found to be favored over the binding of ligands in cis (6). Besides its role as an adhesion molecule, Siglec-2/CD22 is a coreceptor that physically interacts with B-cell receptor (BCR) and is rapidly phosphorylated upon BCR ligation. It negatively regulates BCR signals by recruiting tyrosine phosphatase SHP-1 to its ITIMs. Phosphorylated Siglec-2/CD22 can also interact with other intracellular effector proteins such as Syk, PLC gamma, PI3 kinase and Grb-2, suggesting it may play a role in positive signaling (7-9). Another function of CD22 is that it mediates the anti-phagocytic effect of alpha 2,6-linked sialic acid, and inhibition of CD22 promotes the clearance of myelin debris, amyloid-beta oligomers and alpha -synuclein fibrils in vivo(10). CD22 also plays a role in autoimmunity and has great potential for CD22-based immunotherapeutics for the treatment of autoimmune diseases such as systemic lupus erythematosus (SLE) (11).

References

Crocker, P.R. et al. (2007) Nat. Rev. Immunol. 7:255.
Poe, J.C. and T.F. Tedder (2012) Trends Immunol. 33:413.
Meyer, S.J. et al. (2018) Front. Immunol. 9:2820.
Wilson, G.L et al. (1991) J. Exp. Med. 173:137.
Stamenkovic, I. and B. Seed (1990) Nature 345:74.
Collins, B.E. et al. (2004) Proc. Natl. Acad. Sci. 101:6104.
Crocker, P.R. and A. Varki (2001) Immunology 103:137.
Ravetch, J.V. and L.L. Lanier (2000) Science 290:84.
Wienands, Y.J. et al. (1999) J. Biol. Chem. 274:18769.
Pluvinage, J.V. et al. (2019) Nature. 5568:7751.
Clark, E.A. et al. (2018) Front. Immunol. 9:2235.

Long Name

Sialic Acid Binding Ig-like Lectin 2

Entrez Gene IDs

933 (Human); 12483 (Mouse); 308501 (Rat); 102130968 (Cynomolgus Monkey)

Alternate Names

B-cell receptor CD22; BL-CAM; B-lymphocyte cell adhesion molecule; CD22 antigenMGC130020; CD22 molecule; CD22; sialic acid binding Ig-like lectin 2; Sialic acid-binding Ig-like lectin 2; Siglec2; Siglec-2; SIGLEC2FLJ22814; T-cell surface antigen Leu-14