title: Identification of an epitope of tumor necrosis factor (TNF)-receptor type 1 (p55) recognized by a TNF-alpha-antagonist monoclonal antibody.
abstract: The relationships between epitope topography and agonistic/antagonistic effects of anti-TNF receptor type 1 (TNF-R1) antibodies on TNF-alpha cytotoxic activity have been studied. To this purpose various monoclonal antibodies (mAbs) against the soluble form of TNF-R1 (sTNF-R1) have been generated and characterized. Epitope topography studies identified at least four distinct epitopes located outside (4E10) or within (or close to) the TNF-alpha binding site of urinary sTNF-R1 (7H3, 4C1, 9B11). mAbs 7H3 and 4C1 were able to neutralize the inhibition of human TNF-alpha cytotoxicity on L-M cells by sTNF-R1, while 4E10 was unable. Moreover, 7H3 and 4C1 were able to antagonize the TNF-alpha cytotoxicity on human U937 cells, while they were uneffective on mouse L-M cells, suggesting that these antibodies recognize, in a species-specific mode, also the membrane form of the human receptor. No agonistic effects were observed when these antibodies were used in the absence of TNF-alpha. Epitope topography studies carried out using overlapping decapeptides covering most of the sTNF-R1 sequence showed that residues 143-148 of the fourth cysteine-rich domain of the receptor (FFLREN) contain antigenic determinants recognized by the antagonist antibody 7H3. These results suggest that at least part of residues 143-148 of sTNF-R1 are surface exposed on the soluble as well as on the membrane forms of TNF-R1 and are accessible to TNF-alpha antagonists.
authors.affiliation: Molecular Immunology and Biochemistry Unit, Tecnogen ScpA, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Corti
authors.forename: L
authors.initials: L
authors.lastname: Bagnasco
authors.forename: G
authors.initials: G
authors.lastname: Cassani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D000918:Antibody Specificity; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D005260:Female; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D018124:Receptors, Tumor Necrosis Factor / Q000819:agonists / Q000037:antagonists & inhibitors / Q000276:immunology*; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000633:toxicity
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha