DESCRIPTION

CD28 (T-cell-specific surface glycoprotein CD28), or T44 and Tp44, is a member of the immunoglobulin superfamily and is expressed on most T lineage cells, NK cell subsets, and plasma cells. CD28 may affect in vivo immune responses as a cell adhesion molecule linking B and T lymphocytes and as the surface component of a novel signal transduction pathway. CD28 binds both CD80 and CD86 with a highly conserved motif MYPPY in the CDR3-like loop. In addition, CD28 is considered a major co-stimulatory molecule, inducing T lymphocyte activation and IL-2 synthesis, and preventing cell death.

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 20 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 24 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	20	2,819.2	111.2	3.9
2	20	655.4	18.8	2.9
3	20	173.1	11.1	6.4

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	24	2,635.7	141.8	5.4
2	24	664.8	29.7	4.5
3	24	154.5	13.7	8.8

RECOVERY

The recovery of human CD28 spiked to three different levels throughout the range of the assay in human serum was evaluated.

Sample Type		Average% of Expected	Range (%)
Human serum	1:2	94	88-102
	1:4	103	86-126

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.

		Human serum
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	104
	Range (%)	89-118
1:8	Average% of Expected	106
	Range (%)	83-128
1:16	Average% of Expected	128
	Range (%)	127-129

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human CD28 produced at Sunlong Medical™.

Ordering & shipping

• Minimum order: 1 kit
• Lead time: varies with order quantity and specifications. Please consult your local distributor or our sales team for confirmation
• Payment: T/T 100% in advance; PayPal; Alibaba Trade Assurance
• Shipping: FedEx / DHL / UPS express; cold-chain packing available on request
• Price: USD, per kit (48T / 96T options available)