Anti-Mouse CD22 (Clone MB22-11) – Biotin

Mouse CD22 cDNA-transfected baby hamster kidney cells

This Biotinylated antibody is formulated in 0.01 M phosphate buffered saline (150 mM NaCl) PBS pH 7.4, 1% BSA and 0.09% sodium azide as a preservative.

Liquid

This biotinylated antibody is stable when stored at 2-8°C. Do not freeze.

Research Use Only

2-8°C Wet Ice

MB22-11 activity is directed against mouse CD22 (Siglec-2).

Siglecs (sialic acid-binding immunoglobulin superfamily lectins) are a family of single pass, transmembrane cell surface proteins characterized by shared structural motifs and an ability to recognize sialic acids^{1, 2}. CD22 (Siglec-2), a 140 kDa member of the Siglec family expressed by B cells^{3, 4}, contains six C2-set domains, one V-set domain, and in its intracellular cytoplasmic tail has three immunoreceptor tyrosine-based inhibition motifs (ITIM) and one ITIM-like domain⁵. While murine Siglecs are not necessarily homologous to human Siglecs, CD22 is evolutionarily conserved and does have a direct human ortholog⁵.

CD22 acts as an inhibitory B cell co-receptor that negatively regulates B cell activation, B reg cell expansion, and B cell receptor (BCR) signaling⁴. Upon ligation of BCR, ITIMs are phosphorylated, leading to recruitment and activation of SH2-containing phosphatases that then dephosphorylate signaling molecules activated by BCR ligation⁴. Additionally, CD22 regulates B cell response to inflammation and is a master regulator of microglial phagocytosis in the aging brain⁵.

Evidence in mouse models suggests CD22 contributes to the pathogenesis of autoimmune diseases³. Loss of CD22 leads to hyperactivation of B cells⁵. CD22 mouse knockouts are defective in B cell development but do not develop lupus-like disease⁴.

To generate MB22-11, CD22 knockout mice were immunized with mouse CD22 cDNA-transfected baby hamster kidney cells⁶. Spleen cells were fused with NS-1 myeloma cells, and hybridomas producing antibody specifically reactive with CD22-transfected mouse L cells were selected and purified. MB22-11 was isotyped as IgG2c due to its C57BL/6 origin; however, both IgG2a and IgG2c specific reagents have significant reactivity against MB22-11.

In vitro, MB22-11 inhibits CD22-mediated adhesion by 90% and completely blocks CD22-Fc binding to T and B cells⁶. In vivo, MB22-11 significantly reduces peripheral blood, lymph node, and marginal zone B cell numbers^{6, 7}. Additionally, in mice injected with MB22-11, blood, spleen, and lymph node B cell turnover is higher relative to injection with non-blocking monoclonal antibodies, and B cell surface expression of CD22 is reduced to nearly undetectable levels⁶.

CD22 is expressed by most mature B cell lineages.

SHP-1, Syk, Lck, and Lyn

1. Bochner BS. Clin Exp Allergy. 39(3):317-324. 2009.
2. Kiwamoto T, Kawasaki N, Paulson JC, et al. Pharmacol Ther. 135(3):327-336. 2012.
3. Dörner T, Shock A, Smith KG. Int Rev Immunol. 31(5):363-378. 2012.
4. Tsubata T. Immunol Med. 42(3):108-116. 2019.
5. Siddiqui SS, Matar R, Merheb M, et al. Cells. 8(10):1125. 2019.
6. Haas KM, Sen S, Sanford IG, et al. J Immunol. 177(5):3063-3073. 2006.
7. Haas KM, Watanabe R, Matsushita T, et al. J Immunol. 184(9):4789-4800. 2010.