Analysis of interleukin 6 (IL-6)/IL-6 receptor system using monoclonal anti-IL-6 antibodies.
To investigate the IL-6/IL-6 receptor system, we obtained five murine monoclonal antibodies against human IL-6, which neutralize its biological activity. We classified them into two groups (Type I mAb and Type II mAb) according to the epitopes they recognized. These two types of antibodies showed no difference in the manner in which they neutralized IL-6 activity, but they differed in the way they inhibited the binding of IL-6 to its receptor. While Type I mAb inhibited IL-6 binding to its receptor completely, Type II mAb inhibited only partially, even at a concn of Type II mAb sufficient to neutralize biological activity. Scatchard plot analysis revealed that in the case of the human myeloma cell line, the U266 cell, which showed two-phase binding of IL-6 to its receptor, the high affinity binding disappeared and the affinity of the low affinity binding decreased in the presence of Type II mAb. These results suggest that Type I mAb neutralizes IL-6 activity by the blocking of IL-6 binding to its receptor directly. In contrast, Type II mAb neutralizes IL-6 activity not by direct blocking of IL-6 binding to its receptor, but by modulating the binding affinity of IL-6 to its receptor, that is, inhibiting the formation of high affinity binding in IL-6 receptor system. This also indicates that the formation of high affinity may be necessary to transduce the IL-6 signal.
Shimamura
T
T
Central Research Laboratories, Ajinomoto Co. Inc., Kawasaki, Japan.
Taki
S
S
Honda
H
H
Yokota
M
M
Ito
S
S
Takahara
Y
Y
D000911:Antibodies, Monoclonal; D000915:Antibody Affinity; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D000939:Epitopes / Q000502:physiology; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D009101:Multiple Myeloma / Q000378:metabolism; D011971:Receptors, Immunologic / Q000276:immunology*; D019947:Receptors, Interleukin-6
D000911:Antibodies, Monoclonal; D000939:Epitopes; D015850:Interleukin-6; D011971:Receptors, Immunologic; D019947:Receptors, Interleukin-6