DESCRIPTION

Endothelial cell-selective adhesion molecule (ESAM) is a member of the immunoglobulin superfamily of cell adhesion molecules that is predominantly expressed on vascular endothelial cells and platelets. As a transmembrane adhesion protein, ESAM localizes primarily to intercellular junctions, where it contributes to the regulation of endothelial barrier integrity, cell-cell adhesion, and vascular permeability. ESAM also plays important roles in angiogenesis, vascular development, inflammatory responses, and immune cell trafficking. Beyond its physiological functions, altered ESAM expression has been associated with tumor angiogenesis, cardiovascular diseases, inflammatory disorders, and hematologic malignancies.

PRINCIPLE OF THE ASSAY

An anti-tag antibody is pre-coated onto the bottom of wells. After adding antigen or samples, Tagged-Capture antibody and HRP-conjugated detection antibody, a sandwich complex is formed in the solution. TMB acts as a HRP substrate, and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns the 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 (pg/mL)	SD	CV%
1	8	1,299.1	28.2	2.2
2	8	328.1	5.3	1.6
3	8	173.6	4.5	2.6

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	1,303.1	24.5	1.9
2	16	330.8	6.6	2.0
3	16	175.4	4.7	2.7

RECOVERY

The recovery of human ESAM spiked to three different levels throughout the range of the assay in human serum was evaluated.

Sample Type		Average% of Expected	Range (%)
Human serum	1:64	103	102-104
	1:128	109	102-114

LINEARITY

To assess the linearity of the assay, samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (The human serum was initially diluted 1:8.)

		Human serum
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	109
	Range (%)	107-111
1:8	Average% of Expected	114
	Range (%)	108-119
1:16	Average% of Expected	121
	Range (%)	116-126

CALIBRATION

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