Neutralizing monoclonal antibodies can potentiate IL-5 signaling.
IL-5 is a major determinant in the survival, differentiation and effector-functions of eosinophils. It mediates its effect upon binding and activation of a membrane bound receptor (R), composed of a ligand-specific alpha-chain and a beta-chain, shared with the receptors for IL-3 and granulocyte-macrophage colony-stimulating factor. We have generated and mapped the epitopes of three monoclonal antibodies (mAb) directed against this cytokine: the strong neutralizing mAb 5A5 and 1E1, and the very weak neutralizing mAb H30. We found that H30 as well as 5A5 can increase proliferation above the level induced by human (h)IL-5 alone, in a JAK-2-dependent manner, and at every sub-optimal hIL-5 concentration analyzed. This effect is dependent on mAb-mediated cross-linking of IL-5R complexes, and is only observed on cell lines expressing a hybrid human/mouse IL-5Ralpha-chain. We discuss these findings in view of the stoichiometric and topological requirements for an activated IL-5R. Since humanized anti-IL-5 mAb are currently in clinical testing, our findings imply that such mAb should be carefully evaluated for their potentiating effects.
Zabeau
L
L
Flanders Interuniversity Institute for Biotechnology, Department of Medical Protein Research (VIB09), Ghent University, Ghent, Belgium.
Van der Heyden
J
J
Broekaert
D
D
Verhee
A
A
Vandekerckhove
J
J
Wu
S J
SJ
Chaiken
I
I
Heinrich
P
P
Behrmann
I
I
Tavernier
J
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004306:Dose-Response Relationship, Immunologic; D004357:Drug Synergism; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology; D006801:Humans; D006822:Hybrid Cells / Q000187:drug effects / Q000378:metabolism; D007140:Immunoglobulin Fab Fragments / Q000276:immunology / Q000494:pharmacology; D015848:Interleukin-5 / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology*; D053614:Janus Kinase 2; D051379:Mice; D008954:Models, Biological; D008958:Models, Molecular; D009500:Neutralization Tests; D011487:Protein Conformation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D051381:Rats; D011940:Receptor Aggregation / Q000187:drug effects; D018123:Receptors, Interleukin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053649:Receptors, Interleukin-5; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D015848:Interleukin-5; D011518:Proto-Oncogene Proteins; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; C507927:Jak2 protein, rat; D053614:Janus Kinase 2