Mapping of monoclonal antibody-defined epitopes associated with carcinoembryonic antigen, CEA

Abstract

Six immunoglobulin G monoclonal antibodies reactive with carcinoembryonic antigen (CEA) were evaluated with respect to parameters implicated in their potential diagnostic application and use as tumor targeting agents for cytotoxic drugs or plant or bacterial toxins. Antibody reactivity with surface antigens of the MKN-45 gastric tumor cell line was demonstrated by flow cytofluorimetry. In a subcellular membrane binding assay, each antibody reacted preferentially with membranes isolated from colorectal tumor tissue in comparison with their reaction with membranes from adjacent, apparently normal colonic mucosa. Three of the antibodies (NCRC-23, C228, and 11.285.14) reacted specifically with CEA with little or no reaction with the cross-reacting antigen, NCA. The remaining three antibodies (C24, C161, and C198) were reactive with both CEA and NCA. Analysis of the epitopes defined by these antibodies was performed by competitive binding inhibition assays evaluating the capacity of unlabeled antibodies to compete with 125I-labeled antibodies in their binding to CEA. In addition, double determinant or 'sandwich' radioimmunoassays were employed to examine the coexpression of epitopes on CEA molecules. These studies permitted an epitope map to be constructed which describes the coincidence, overlapping, or independent expression of both CEA specific epitopes and epitopes shared between CEA and NCA. The map may be employed for the selection of antibodies for diagnostic and therapeutic use.

C595 – a monoclonal antibody against the protein core of human urinary epithelial mucin commonly expressed in breast carcinomas

“…The following murine antibodies were also used: C365 -IgGl (anti-carcinoembryonic antigen, CEA); C161 -IgGI (anti-normal cross-reacting antigen, NCA); C14 -1gM (anti-Y hapten, Ley) (Price et al, 1987b) Antigen preparations NCRC-1 1 defined antigen preparations were isolated from detergent (Nonidet P-40) solubilised subcellular membranes from breast carcinomas and ovarian mucinous and serous carcinomas by immunoadsorbent chromatography using Sepharose-linked NCRC-l 1 antibodies as previously described (Price et al, 1985(Price et al, , 1986b. Samples of skim milk and normal urine were also employed as the starting material for NCRC-l 1 defined antigen isolation although detergent was not included in the initial sample solution or washing buffers (Price et al, 1987a).…”

Immune responses to the 105AD7 human anti-idiotypic vaccine after intensive chemotherapy, for osteosarcoma

“…CD55 and CEA were purified from 791Tcells and colorectal tumours using previously described methods (Price et al, 1987;Spendlove et al, 1999) and used to coat microtitre plates by overnight incubation at room temperature. Plates were blocked with phosphate buffer and saline (PBS) containing 1% bovine serum albumin (BSA).…”

Enhanced recognition of human colorectal tumour cells using combinations of monoclonal antibodies

“…C14 is an IgM monoclonal antibody which recognises the Y haptenic blood group antigen expressed by the majority of colon adenocarcinomas (Brown et al, 1983). 161 is an IgG, monoclonal antibody that recognises a similar epitope expressed on CEA and NCA (Price et al, 1987). Finally, 228 monoclonal antibody recognised an epitope only expressed on CEA (Price et al, 1987 (Makin et al, 1984).…”

“…161 is an IgG, monoclonal antibody that recognises a similar epitope expressed on CEA and NCA (Price et al, 1987). Finally, 228 monoclonal antibody recognised an epitope only expressed on CEA (Price et al, 1987 (Makin et al, 1984).…”