title: Development and characterization of a syngeneic monoclonal antibody to a rat mammary tumor metastasis-associated mucin-like cell-surface antigen (gp580).
abstract: A rat hybridoma producing IgM monoclonal antibody (MAb) GP21:56 was generated with specificity for a high-molecular-weight, mucin-like glycoprotein (gp580) present on highly metastatic 13762NF rat mammary adenocarcinoma cells. The hybridoma was made by fusing rat Y3 Ag1.2.3 myeloma cells with spleen cells from a rat immunized i.d. with purified gp580. The gp580 appeared to be of low immunogenicity in syngeneic F344 rats because a total of 27 fusions were required to produce one hybridoma with specificity for this glycoprotein. Immunoblotting of purified gp580 after electrophoresis in 1% agarose and antibody-binding assays using purified gp580 linked to microtiter plates confirmed that MAb GP21:56 bound specifically to gp580. Other MAbs made against breast mucins were negative for gp580 reactivity. Enzyme-linked immunoabsorbent assays (ELISA) and radiolabelled antibody binding assays demonstrated that MAb GP21:56 bound to 13762NF adenocarcinoma cell lines and clones in relation to their spontaneous metastatic potentials; significantly more MAb GP21:56 bound to highly metastatic MTLn3 cells than to low metastatic MTC cells, and MAb GP21:56 showed little reactivity towards the majority of other cell lines tested, whether of rodent or of human origin. Kinetic binding studies indicated that MAb GP21:56 does not have a high affinity for gp580 but, once bound, it shows high avidity for this sialogalactoprotein. Localization studies using frozen tissue sections of 13762NF tumors indicated that MAb GP21:56 reacts with tumor cells grown in vivo in an analogous manner to in vitro cultured cells. Using immunoperoxidase techniques, less than 50% of the highly metastatic MTLn3 tumor cells were stained, whereas approximately 20% of the intermediate metastatic MTF7 and MTLn2 cells and less than 10% of low metastatic MTC and MTPa cells were stained with MAb GP21:56. The cell-to-cell reactivity was heterogeneous and mainly associated with the tumor-cell surface and extracellular matrix.
authors.affiliation: Department of Tumor Biology, University of Texas M.D. Anderson Hospital and Tumor Institute, Houston 77030.
authors.forename: S M
authors.initials: SM
authors.lastname: North
authors.forename: P A
authors.initials: PA
authors.lastname: Steck
authors.forename: W H
authors.initials: WH
authors.lastname: Spohn
authors.forename: G L
authors.initials: GL
authors.lastname: Nicolson
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology*; D000918:Antibody Specificity; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D005260:Female; D037102:Lectins / Q000276:immunology; D008325:Mammary Neoplasms, Experimental / Q000276:immunology*; D008970:Molecular Weight; D009077:Mucins / Q000032:analysis* / Q000276:immunology; D009362:Neoplasm Metastasis; D019887:Peanut Agglutinin; D051381:Rats; D011916:Rats, Inbred F344; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D037102:Lectins; D009077:Mucins; D019887:Peanut Agglutinin