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

Sandwich ELISA structure (Detection antibody labeled with HRP) A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody labeled with HRP also binds to the analyte. 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	965.3	54.8	5.7
2	20	204.4	7.5	3.7
3	20	46.8	3.9	8.3

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	24	1,012.1	58.0	5.7
2	24	243.5	13.0	5.3
3	24	57.6	2.5	4.4

RECOVERY

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

Sample Type		Average% of Expected	Range (%)
Human serum	1:32	88	81-96
	1:64	90	77-99
Urine	1:160	99	92-106
	1:320	99	93-109

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 serum was initially diluted 1:4. The urine was initially diluted 1:20.)

		Human serum	Urine
1:2	Average% of Expected	100	100
	Range (%)	-	-
1:4	Average% of Expected	93	93
	Range (%)	92-95	87-100
1:8	Average% of Expected	104	83
	Range (%)	103-105	78-87
1:16	Average% of Expected	90	72
	Range (%)	88-91	70-75

CALIBRATION

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