DESCRIPTION

CCL27, also known as CTACK, is a member of the CC chemokine subfamily. CCL27 is predominantly expressed in skin and selectively attracts cutaneous lymphocyte antigen-positive T cells and Langerhans cells. The CCL27 secreted from keratinocytes was reportedly involved in inflammatory skin diseases such as atopic dermatitis, contact dermatitis, and psoriasis. CCL27 is a ligand to CCR10. The binding of CCL27 to CCR10 on T cells promotes their migration to the skin, where they can then participate in local immune responses.

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	757.9	14.8	2.0
2	8	179.1	2.0	1.1
3	8	89.6	2.8	3.1

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	772.0	18.9	2.4
2	16	182.2	4.1	2.3
3	16	90.1	2.6	2.9

RECOVERY

The recovery of human CCL27 spiked to three different levels throughout the range of the assay in human plasma was evaluated.

Sample Type		Average% of Expected	Range (%)
Human plasma	1:8	118	115-123
	1:16	116	115-118

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 plasma
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	119
	Range (%)	116-121
1:8	Average% of Expected	121
	Range (%)	120-122
1:16	Average% of Expected	121
	Range (%)	117-125

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human CCL27 produced at Sunlong Medical™.