Mini Sample Mouse CD23 (Receptor Ⅱ for the Fc Region of Immunoglobulin E) ELISA Kit (E-MSEL-M0121)

This ELISA kit uses the Sandwich-ELISA principle. The micro ELISA plate provided in this kit has been pre-coated with an antibody specific to CD23 . Standards or samples are added to the micro ELISA plate wells and combined with the specific antibody. Then a biotinylated detection antibody specific for CD23 and Avidin-Horseradish Peroxidase (HRP) conjugate are added successively to each micro plate well and incubated. Free components are washed away. The substrate solution is added to each well. Only those wells that contain CD23 , biotinylated detection antibody and Avidin-HRP conjugate will appear blue in color. The enzyme-substrate reaction is terminated by the addition of stop solution and the color turns yellow. The optical density (OD) is measured spectrophotometrically at a wavelength of 450 nm ± 46 nm. The OD value is proportional to the concentration of CD23 . You can calculate the concentration of CD23 in the samples by comparing the OD of the samples to the standard curve.

The low affinity receptor for IgE, Fc epsilon RII (designated CD23) is a member of subgroup II of the C-type (Ca2+-dependent) lectin superfamily (1-4). Mouse CD23 is a 45-49 kDa type II transmembrane glycoprotein that binds mouse, but not human, IgE (1-4). The longest isoform is 331 amino acids (aa) in length and contains a 23 aa cytoplasmic domain, a 26 aa transmembrane segment, and a 282 aa extracellular domain (ECD). The ECD C-type lectin domain binds both protein and carbohydrate, with separate sites for binding IgE, CD21, and beta 2 and alpha v integrins (2). Coiled-coil topography within a connecting stalk contributes to oligomerization, which increases IgE affinity (1, 2). Mouse CD23 shares 88% aa identity with rat CD23 and up to 57% aa identity with isoforms of human, equine, porcine and bovine CD23. Isoforms which vary in the cytoplasmic sequence include the “a” isoform, which begins with the sequence MEENEYS and is constitutively expressed by B cells, and the “b” isoform, which begins with MDTHHT and is induced by IL-4 on a variety of inflammatory cells, B cells and epithelia (2, 5-7). The isoforms differentially participate in IgE-mediated endocytosis and phagocytosis (2, 8-10). CD23b and two 309 aa mouse CD23b isoforms, lacking either exon 5 or 6, also display distinct endocytic properties on intestinal epithelia (6, 11). Several soluble forms of CD23 are mainly generated by metalloprotease (especially ADAM10) and cysteine protease digestion, although potentially soluble mouse isoforms have also been sequenced (12-14). Both soluble and membrane-bound forms of CD23 include the lectin domain and show bioactivity. CD23 binding to monocyte integrins results in oxidative product generation and proinflammatory cytokine release (15). On human, but not mouse, B cells, sCD23 induces IgE secretion by binding CD21 (2, 9). In both, secreted IgE will bind B cell membrane CD23, rendering it unavailable for cleavage, and thus shutting down IgE production (2).