DESCRIPTION

CD48, also known as BLAST-1 or BCM-1, is a member of the signaling lymphocyte activation molecule (SLAM) family and is involved in immune cell adhesion and activation. It is a glycosylphosphatidylinositol (GPI) -anchored cell surface glycoprotein that interacts with various cell surface receptors, including CD244 (2B4) and CD2. CD48 plays a crucial role in regulating immune responses by mediating cell-cell interactions and signaling pathways that influence T cell activation, NK cell function, and the formation of immune synapses. Soluble CD48 (sCD48) is detected in human serum and plasma. sCD48 may serve as a potential therapeutic agent for inflammatory diseases by modulating immune cell activation and cytokine signaling.

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	1,305.3	29.6	2.3
2	8	326.0	10.7	3.3
3	8	166.6	2.4	1.4

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	1,298.3	39.4	3.0
2	16	324.8	12.0	3.7
3	16	163.0	4.7	2.9

RECOVERY

The recovery of human CD48 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Human plasma	1:8	94	90-97
	1:16	101	91-112
Cell culture supernatant	1:2	89	86-92
	1:4	92	89-95
Cell lysate	1:16	89	85-92
	1:32	88	83-96

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 cell lysate was initially diluted 1:8.)

		Human plasma	Cell culture supernatant	Cell lysate
1:2	Average% of Expected	100	100	100
	Range (%)	-	-	-
1:4	Average% of Expected	108	105	92
	Range (%)	106-110	102-109	91-93
1:8	Average% of Expected	110	113	95
	Range (%)	110-111	111-115	91-99
1:16	Average% of Expected	118	115	100
	Range (%)	116-119	112-118	97-104

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human CD48 produced at Sunlong Medical™.