DESCRIPTION

Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a co-inhibitory receptor that plays a crucial role in regulating T-cell activation and maintaining immune tolerance and delivers inhibitory signals that suppress T-cell responses, thereby preventing autoimmune diseases. It is expressed on activated T cells and regulatory T cells (Tregs), which mediates its inhibitory function by competing with CD28 for binding to CD80/CD86, depleting these ligands from antigen-presenting cells (APCs) and dendritic cells (DCs), and delivering inhibitory signals via its intracellular tail. CTLA-4 exists in two forms: membrane-bound CTLA-4 (mCTLA4) and soluble CTLA-4 (sCTLA-4). mCTLA-4 is a transmembrane protein localized on the surface of T cells and Tregs, where it interacts with CD80 and CD86 on APCs. sCTLA-4 lacks the transmembrane domain and is released into the extracellular environment, where it can modulate immune responses.

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 (pg/mL)	SD	CV%
1	8	850.4	29.6	3.5
2	8	177.4	8.2	4.6
3	8	92.5	7.6	8.2

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	800.1	60.7	7.6
2	16	181.3	9.1	5.0
3	16	91.7	7.5	8.1

RECOVERY

The recovery of mouse CTLA-4 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Mouse serum	1:2	74	70-77
Tissue lysate	1:128	99	93-103
	1:256	88	85-94

LINEARITY

To assess the linearity of the assay, mouse serum samples were spiked with high concentrations of mouse CTLA-4 and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. Tissue lysate samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (The tissue lysate was initially diluted 1:8. )

		Mouse serum	Tissue lysate
1:2	Average% of Expected	87	100
	Range (%)	82-95	-
1:4	Average% of Expected	93	100
	Range (%)	91-96	99-102
1:8	Average% of Expected	96	98
	Range (%)	92-99	82-106
1:16	Average% of Expected	105	100
	Range (%)	98-110	87-106

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant mouse CTLA-4 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)