DESCRIPTION

Trefoil factor 1 (TFF1) is also named as PNR-2, Polypeptide P1.A (hP1.A), Breast cancer estrogen-inducible protein (BCEI) and Protein pS2. TFF1 is one of three members of the trefoil factor family. While abundant TFF1 expression can be observed in the gastrointestinal epithelium, it is also expressed in other organs, such as the ileum, colon, and pancreas. The known function of TFF1 is to promote the regeneration of gastric mucosa induced by inflammatory injury by encouraging epithelial cell migration, and a similar regenerative effect is also found in the pancreas and liver. Importantly, recent studies have revealed that TFF1 also functions as a tumor suppressor to inhibit gastric, pancreatic, and hepatocellular carcinogenesis, presumably by inhibiting the Wnt/β-catenin pathway. In terms of the esophagus, TFF1 is not expressed in the squamous epithelium of the esophagus but is expressed in the submucosal gland and BE.

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	1,102.0	45.5	4.1
2	8	262.5	15.8	6.0
3	8	124.3	5.0	4.0

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	1,069.2	55.0	5.1
2	16	257.1	16.4	6.4
3	16	123.2	6.8	5.5

RECOVERY

The recovery of human TFF1 spiked to three different levels throughout the range of the assay in human plasma was evaluated.

Sample Type		Average% of Expected	Range (%)
Human plasma	1:16	81	74-92

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. (The human plasma was initially diluted 1:4.)

		Human plasma
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	98
	Range (%)	97-100
1:8	Average% of Expected	87
	Range (%)	86-88
1:16	Average% of Expected	70
	Range (%)	70-71

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human TFF1 produced at Sunlong Medical™.