DESCRIPTION

The polymeric immunoglobulin receptor (PIGR), an integral membrane protein, is required for transcytosis of polymeric immunoglobulins (pIg) including IgA and IgM across mucosal epithelial cells. PIGR is expressed on the basolateral surface of ciliated epithelial cells in the mucosal epithelium. Upregulation of PIGR expression has been well documented with a variety of proinflammatory cytokines such as IFN-γ and IL-1α.

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	2,567.0	40.2	1.6
2	8	638.3	14.8	2.3
3	8	307.5	7.5	2.4

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	2,564.1	77.6	3.0
2	16	634.6	14.8	2.3
3	16	303.4	9.3	3.1

RECOVERY

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

Sample Type		Average% of Expected	Range (%)
Human serum	1:8	99	82-126
	1:16	89	83-98

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 serum
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	97
	Range (%)	95-99
1:8	Average% of Expected	101
	Range (%)	98-104
1:16	Average% of Expected	105
	Range (%)	103-108

CALIBRATION

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