CA 27.29

CLINICAL UTILITY:

Breast carcinoma-associated antigen coded by the human MUC-1 gene is identified by several names including MAM6, milk mucin, polymorphid epithelial mucin, PEM, CA27.29 and CA1503. As indicated by epitope mapping, inhibition of antibody binding, tracer exchange and clinical studies, CA27.29 and CA15-3 epitopes overlap. This antigen is a glycoprotein (molecular weight 300-450 kDa), which contains a 20 amino acid tandem repetitive sequence of the mucin core. Carbohydrates comprise more than half of the molecule. The number of tandem repeats and the degree of glycosylation is variable between individuals, so that CA27.29 is very heterogeneous in structure. In malignant cells, Ca27.29 is over expressed on the entire surface, and increasing amounts are shed into the circulation. Tumors involving glandular organs, such as the breast, can produce high concentration of Ca27.29 in serum, making it useful as a tumor marker. Monoclonal antibodies that recognized distinct epitopes on CA27.29 and CA15-3 antigen molecules have been used to develop immunoassays.

AIA-PACK 27.29 was developed with a monoclonal antibody that recognizes an 8 amino acid section in the tandem repeat portion of the polypeptide chain. Since the antigen levels correlated closely with disease regression or progression, CA27.29 proved reliable in the follow-up of patients with advanced beast cancer.

METHOD DESCRIPTION:

To assay for serum ca 27.29 levels, a solid phase enzyme immunoassay (EIA) based on the "sandwich" principle is used.

REFERENCE RANGE:

<38 U/mL

SPECIMEN REQUIREMENTS:

2.0 ml serum (red top tube, minimum volume is 0.3 ml).