DESCRIPTION

Mammaglobin A, also known as SCGB2A2, is a member of the secretoglobin superfamily. Mammaglobin A is expressed in normal mammary gland epithelium and is over-expressed in primary and metastatic human breast cancers, making it a specific molecular marker and a potential therapeutic target for breast cancer. Secreted Mammaglobin protein has been detected in the sera of some breast cancer patients and not in sera of patients with other tumor types, indicating Mammaglobin as a serum marker for breast cancer.

PRINCIPLE OF THE ASSAY

A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody also binds to the analyte. Horseradish peroxidase (HRP)-conjugated secondary antibody binds to the detection antibody. 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	6,124.8	545.7	8.9
2	20	1,593.5	105.5	6.6
3	20	343.8	20.1	5.8

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	24	5,411.6	483.5	8.9
2	24	2,572.7	133.4	5.2
3	24	485.1	22.9	4.7

RECOVERY

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

Sample Type		Average% of Expected	Range (%)
Human plasma	1:4	99	92-106
	1:8	106	102-111
Cell culture supernatant	1:2	103	86-125
	1:4	105	91-115
Urine	1:2	100	92-113
	1:4	87	85-90

LINEARITY

To assess the linearity of the assay, three samples were spiked with high concentrations of human Mammaglobin A in various matrices and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (The human plasma samples were initially diluted 1:2)

		Human plasma	Cell culture supernatant	Urine
1:2	Average% of Expected	88	82	113
	Range (%)	85-90	80-83	103-130
1:4	Average% of Expected	95	102	111
	Range (%)	86-103	96-112	105-120
1:8	Average% of Expected	100	93	103
	Range (%)	92-107	90-97	98-111
1:16	Average% of Expected	98	104	101
	Range (%)	91-104	101-108	97-106

CALIBRATION

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