DESCRIPTION

CD300A is an inhibitory receptor expressed on various leukocytes. It plays a crucial role in modulating immune responses by recognizing phosphatidylserine (PS) and phosphatidylethanolamine (PE), two aminophospholipids exposed on the outer leaflet of dead and activated cells. This recognition helps regulate immune functions and the host's response to various disease states, such as infectious diseases, cancer, allergies, and chronic inflammatory diseases. CD300A delivers inhibitory signals through its immunoreceptor tyrosine-based inhibitory motifs (ITIMs), which are phosphorylated upon ligand binding and recruit SH2containing phosphatases, leading to the inhibition of downstream signaling pathways.

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	2,065.3	121.7	5.9
2	8	509.5	18.0	3.5
3	8	167.1	5.2	3.1

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	2,078.5	110.8	5.3
2	16	513.6	17.9	3.5
3	16	166.7	5.3	3.2

RECOVERY

The recovery of human CD300A spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Human plasma	1:16	97	91-105
	1:32	107	103-112
Urine	1:64	110	108-113
	1:128	109	107-110
Cell lysate	1:64	78	77-80
	1:128	83	82-84

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 plasma was initially diluted 1:2. The urine was initially diluted 1:8. The cell lysate was initially diluted 1:8.)

		Human plasma	Urine	Cell lysate
1:2	Average% of Expected	100	100	100
	Range (%)	-	-	-
1:4	Average% of Expected	109	108	94
	Range (%)	105-112	105-111	93-96
1:8	Average% of Expected	112	106	95
	Range (%)	107-117	106-107	92-98
1:16	Average% of Expected	113	95	91
	Range (%)	101-124	93-98	88-93

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human CD300A produced at Sunlong Medical™.