DESCRIPTION

CD22, also known as Siglec-2 (sialic acid binding Ig-like lectin 2) or BL-CAM (B-lymphocyte cell adhesion molecule), is a 130-140 kDa, B-cell restricted, type I transmembrane glycoprotein belonging to the immunoglobulin gene superfamily. The expression of CD22 is developmentally regulated. It is expressed at low levels in the cytoplasm of pro-B and pre-B cells and present on the cell surface only at mature stages of B-cell differentiation. Cell surface expression is lost during terminal differentiation into plasma cell and after B-cell activation. CD22 is an inhibitory receptor for B-cell receptor (BCR) signalling, preferentially binds to alpha-2,6-linked sialic acid and mediates B-cell B-cell interactions. It plays a crucial role in activation and differentiation of the Bcell. Soluble form of CD22 (sCD22) has been found in human serum and may be useful as a tumor marker for hairy cell leukemia.

PRINCIPLE OF THE ASSAY

Sandwich ELISA structure (Detection antibody labeled with HRP) A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody labeled with HRP also binds to the analyte. TMB acts as the HRP substrate and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns solution yellow. The color intensity is proportional to the quantity of bound protein which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 8 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 16 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	8	4.74	0.15	3.21
2	8	1.21	0.04	2.92
3	8	0.63	0.01	1.48

Inter-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	16	4.50	0.28	6.29
2	16	1.25	0.04	3.41
3	16	0.66	0.04	6.33

RECOVERY

The recovery of human CD22 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Human plasma	1:2	76	73-82
Cell lysate	1:512	82	73-87

LINEARITY

To assess the linearity of the assay, human plasma samples were spiked with high concentrations of human CD22 and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. Cell lysate samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (TThe cell lysate was initially diluted 1:64.)

		Human plasma(Sample Diluent PT 5-ef)	Cell lysate(Sample Diluent PT 4B1)
1:2	Average% of Expected	82	100
	Range (%)	79-85	-
1:4	Average% of Expected	89	106
	Range (%)	87-90	103-110
1:8	Average% of Expected	92	112
	Range (%)	91-92	110-115
1:16	Average% of Expected	102	114
	Range (%)	100-103	111-119

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human CD22 produced at Sunlong Medical™.

Ordering & shipping

• Minimum order: 1 kit
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