DESCRIPTION

Kidney injury molecule 1 (KIM-1), also known as Hepatitis A virus cellular receptor 1 (HAVCR1) or T-cell immunoglobulin and mucin domain 1 (TIM-1), is a class I integral membrane glycoprotein, with an ectodomain containing Ig-like domain and a mucin domain. KIM-1 acts as a membrane receptor for hepatitis A virus (HAV). KIM-1 provides a costimulatory signal for T cell activation and inhibits the development of peripheral tolerance. KIM-1 may be involved in the regulation of asthma and allergic diseases. It has been reported that KIM-1 is shed into urine after acute kidney damage and is a marker of renal tubular injury.

PRINCIPLE OF THE ASSAY

Sandwich ELISA structure (Detection antibody labeled with biotin) A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody labeled with biotin also binds to the analyte. Streptavidin-HRP binds to the biotin. 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	629.9	20.5	3.3
2	20	141.8	3.2	2.2
3	20	29.2	1.8	6.1

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	24	635.9	30.1	4.7
2	24	145.9	6.3	4.3
3	24	33.5	2.4	7.2

RECOVERY

The recovery of human KIM-1/HAVCR1 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average % of Expected	Range (%)
Human plasma	1:2	86	71-111
	1:4	98	90-110
Cell culture supernatant	1:2	98	85-114
	1:4	105	99-123
Urine	1:4	95	77-120
	1:8	102	89-121

LINEARITY

To assess the linearity of the assay, human plasma samples were spiked with high concentrations of KIM-1/HAVCR1 in various matrices and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. Cell culture supernatant and urine was diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay.

		Human plasma	Cell culture supernatant	Urine
1:2	Average% of Expected	83	100	100
	Range (%)	72-94	-	-
1:4	Average% of Expected	90	110	105
	Range (%)	76-116	107-114	101-109
1:8	Average% of Expected	91	120	105
	Range (%)	81-100	118-123	100-110
1:16	Average% of Expected	97	122	96
	Range (%)	89-115	120-124	76-119

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human Human KIM-1/HAVCR1 Sandwich ELISA Kit produced at Sunlong Medical™.