DESCRIPTION

The C-C motif chemokine ligand 22 (CCL22), also known as MDC, belongs to the group of chemokines, that are both constitutively expressed under homeostatic conditions and inducible upon inflammation. CCL22 is a secreted protein that exerts chemotactic activity for monocytes, dendritic cells, natural killer cells, and for chronically activated T lymphocytes. CCL22 is induced by LPS, IL-4, and IL-13 and in T cells by TCR stimulation.

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	251.2	6.7	2.7
2	20	56.3	2.5	4.5
3	20	12.2	1.2	9.5

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	24	215.9	20.9	9.7
2	24	55.7	3.4	6.0
3	24	12.7	1.3	9.9

RECOVERY

The recovery of mouse CCL22 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Mouse serum	1:4	97	85-116
	1:8	108	87-121
Cell culture supernatant	1:4	111	105-124
	1:8	90	83-96

LINEARITY

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

		Mouse serum	Cell culture supernatant
1:2	Average% of Expected	100	100
	Range (%)	-	-
1:4	Average% of Expected	106	95
	Range (%)	97-111	91-102
1:8	Average% of Expected	109	91
	Range (%)	87-123	84-96
1:16	Average% of Expected	109	-
	Range (%)	101-123	-

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant mouse CCL22 produced at Sunlong Medical™.