DESCRIPTION

Interleukin-2 (IL-2) is a four-helix bundle, type I cytokine that functions as a growth factor for a wide range of leukocytes. In the immune system, IL-2 is essential for immune homeostasis, normal T regulatory cell function and development, maintenance. It regulates immune cell homeostasis and has been used to treat a range of disorders including cancer and autoimmune disease. IL-2 signal is mediated through heterodimerization of the IL2Rβ and Il-2Rγ receptor subunits.

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	409.2	5.1	1.3
2	8	101.1	1.3	1.3
3	8	51.7	1.1	2.1

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	410.1	4.1	1.0
2	16	102.8	2.4	2.3
3	16	52.5	1.4	2.7

RECOVERY

The recovery of Mouse IL-2 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	80	73-87
	1:4	92	88-93
Cell culture supernatant	1:2,000	92	90-93
	1:4,000	94	92-98

LINEARITY

To assess the linearity of the assay, mouse serum samples were spiked with high concentrations of mouse IL-2 and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. Cell culture supernatant samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (The cell culture supernatant was initially diluted 1:1,000.)

		Mouse serum(Sample Diluent PT 3-ac)	Cell culture supernatant(Sample Diluent PT 3)
1:2	Average% of Expected	81	100
	Range (%)	79-82	-
1:4	Average% of Expected	91	108
	Range (%)	87-95	107-108
1:8	Average% of Expected	97	112
	Range (%)	93-100	110-114
1:16	Average% of Expected	101	114
	Range (%)	96-107	110-119

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant mouse IL-2 produced at Sunlong Medical™.