Development of a human interleukin-6 receptor antagonist.
Neutralizing monoclonal antibodies specific for human interleukin-6 (IL-6) bind two distinct sites on the IL-6 protein (sites I and II). Their interference with IL-6 receptor binding suggested that site I is a receptor-binding site of IL-6, whereas site II is important for signal transduction. Mutagenesis of site II could therefore result in the isolation of IL-6 receptor antagonists. To test this hypothesis, a panel of IL-6 mutant proteins was constructed that did not bind to a site II-specific monoclonal antibody. One such site II mutant protein (with double substitution of Gln-160 with Glu and Thr-163 with Pro) was found to be an antagonist of human IL-6. It was inactive on human CESS cells, weakly active on human HepG2 cells, but active on mouse B9 cells. It could specifically antagonize the activity of wild-type IL-6 on CESS and HepG2 cells. The binding affinity of this variant for the 80-kDa IL-6 receptor was similar to that of wild-type IL-6. High affinity binding to CESS cells, however, was abolished, suggesting that the mutant protein is inactive because the complex of the 80-kDa IL-6 receptor and the mutant protein cannot associate with the signal transducer gp130. The human IL-6 antagonist protein may be potentially useful as a therapeutic agent.
Brakenhoff
J P
JP
Department of Autoimmune Diseases, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam.
de Hon
F D
FD
Fontaine
V
V
ten Boekel
E
E
Schooltink
H
H
Rose-John
S
S
Heinrich
P C
PC
Content
J
J
Aarden
L A
LA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D051379:Mice; D009154:Mutation; D011485:Protein Binding; D018123:Receptors, Interleukin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019947:Receptors, Interleukin-6; D015398:Signal Transduction
D000911:Antibodies, Monoclonal; D015850:Interleukin-6; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6