A CD66a-specific, activation-dependent epitope detected by recombinant human single chain fragments (scFvs) on CHO transfectants and activated granulocytes

• Published in: Journal of leukocyte biology Vol. 59; no. 6; pp. 891 - 901
• Main Authors: Jantscheff, Peter, Nagel, Gerhard, Thompson, John, Kleist, Sabine V., Embleton, M. J., Price, Michael R., Grunert, Fritz
• Format: Journal Article
• Language: English
• Published: United States Society for Leukocyte Biology 01.06.1996
• Subjects: Animals; Antigens, CD - analysis; Antigens, CD - immunology; Antigens, Differentiation - analysis; Antigens, Differentiation - immunology; biliary glycoproteins; CEA family; Cell Adhesion Molecules; CHO Cells; Cricetinae; Epitopes; HeLa Cells; HL-60 Cells; HL60; Humans; Immunoglobulin Fragments - immunology; N-Formylmethionine Leucyl-Phenylalanine - pharmacology; neuraminidase; Neutrophils - immunology; phorbol myristate acetate; Recombinant Proteins - immunology; Respiratory Burst; retinoic acid; Tetradecanoylphorbol Acetate - pharmacology; Transfection
• ISSN: 0741-5400; 1938-3673
• DOI: 10.1002/jlb.59.6.891

Antibodies to CD66 recognize at least five members (CD66a–e) of the carcinoembryonic antigen (CEA) family. Recombinant human single‐chain Fv fragments (scFvs) that bind specifically to CD66a (biliary glycoprotein) were obtained from a naive human scFv library. The scFvs bound to the N‐domain of CD66a on Chinese hamster ovary (CHO) transfectants but did not bind to freshly isolated peripheral granulocytes or to dimethylsulfoxide‐treated HL‐60 cells. In contrast, scFvs bound well to granulocytes that were short‐term activated with N‐formyl‐Met‐Leu‐Phe or phorbol 12‐myristate 13‐acetate and to human HL‐60 cells that were treated with all‐trans‐retinoic acid to induce granulocytic differentiation. Quantification of antigenic sites showed that the activation‐dependent CD66a epitopes were expressed on nearly all of the CD66a molecules on CHO‐biliary glycoprotein transfectants, but they were detected only on a portion of the molecules on activated polymorphonuclear neutrophils and differentiated HL‐60 cells. Binding of CD66a scFvs to their neoepitopes on prestimulated PMNs induced respiratory burst, suggesting that CD66a is capable of delivering transmembrane signals in these cells.