Biochemical and immunological properties of the human carcinoma-associated CAR-3 epitope defined by the monoclonal antibody AR-3

M. Prat, E. Medico, P. Rossino, C. Garrino, P. M. Comoglio

Research output: Contribution to journalArticlepeer-review

Abstract

The monoclonal antibody AR-3 reacts with an epitope (CAR-3) carried on a high-molecular-weight glycoprotein associated with carcinomas of the pancreas, stomach, colon, uterus, and ovary. This study reports the partial purification and characterization of CAR-3-bearing molecule. The antigen was quantified by a double determinant immunoradiometric assay. CAR-3 antigen was purified by a three-step procedure, consisting of perchloric acid extraction, molecular sieving on Sepharose CL-4B, and affinity chromatography on AR-3 antibodies coupled to Sepharose 4B. Following this procedure CAR-3 antigen was purified about 400-fold with a 36% yield. Treatment of the CAR-3 antigen with 16 mM metaperiodate or with 1 N NaOH resulted in complete loss of activity. Antigenicity survived enzymatic treatments known to destroy proteins. The epitope was found to be carried on a molecule with a molecular weight of > 400,000 with a density of 1.45 g/ml, metabolically labeled with [35S]sulfate, [3H]glucosamine, and [35S]methionine. It is concluded that CAR-3 epitope is expressed on a carbohydrate moiety linked to a sulfo-mucin-like molecule via an O-glycosidic bond. Cross-competition experiments showed that CAR-3 epitope is strictly related or in close topographic proximity to Lewisa and Lewisb antigens. Cross-double determinant immunoradiometric assay experiments indicated that the same mucin carrying CAR-3 bears also CA 19-9, CA 125, and BW 494 epitopes.

Original languageEnglish
Pages (from-to)1415-1421
Number of pages7
JournalCancer Research
Volume49
Issue number6
Publication statusPublished - 1989

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Fingerprint Dive into the research topics of 'Biochemical and immunological properties of the human carcinoma-associated CAR-3 epitope defined by the monoclonal antibody AR-3'. Together they form a unique fingerprint.

Cite this