Characterization of binding and biological effects of monoclonal antibodies against a human tumor necrosis factor receptor.
Three different antibodies against a human TNF receptor (htr-1, htr-5, and htr-9) have been examined for their binding pattern to U937 cells and ability to mimic TNF-alpha activity in U937 cells, Fs4 fibroblasts, and human endothelial cells. Flow cytometric analysis revealed that htr-5 and htr-9 bound specifically to a TNF receptor on U937 cells that could be blocked by pretreatment with rTNF-alpha. Pretreatment of U937 cells with rTNF-beta blocked the binding of htr-9, but to a lesser extent htr-5 binding. Pretreatment with htr-5 inhibited the binding of htr-9 to U937 cells while pretreatment with htr-9 did not inhibit htr-5 binding. These results indicate that htr-5 and htr-9 recognize distinct but overlapping epitopes of a human TNF receptor on U937 cells and that htr-5 may be close to a TNF-alpha-specific domain of the binding site. Pretreatment with htr-5 or htr-9 only minimally reduced binding of BrTNF-alpha to U937 cells; however, these antibodies were much more effective in inhibiting BrTNF-alpha binding to HL-60 cells. Furthermore, it was found that htr-1 and htr-9, but not htr-5, had TNF-alpha activity on U937 cells, Fs4 fibroblasts, and endothelial cells and that the TNF-alpha activity induced by htr-9 was completely inhibited by htr-5. However, the cytotoxic activity of TNF-alpha was only partially inhibited by htr-5 on U937 cells while htr-5 had no effect on TNF-alpha activity on Fs4 cells. The data suggest that a common epitope is involved in inducing TNF-alpha activity in three different cell systems.
Espevik
T
T
Institute of Cancer Research, University of Trondheim, Norway.
Brockhaus
M
M
Loetscher
H
H
Nonstad
U
U
Shalaby
R
R
D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D000939:Epitopes / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D008233:Lymphotoxin-alpha / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000276:immunology*; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D008233:Lymphotoxin-alpha; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha