Characterization of a monoclonal antibody directed against the NH2 terminal area of interleukin-2 (IL-2) and inhibiting specifically the binding of IL-2 to IL-2 receptor beta chain (IL-2R beta).
An anti-human IL-2 mAb (19B11/beta) was found to selectively block the binding of IL-2 to TS1 beta cells expressing the interleukin-2 receptor beta (IL-2R beta) without affecting binding to TS1 alpha cells expressing the IL-2R alpha receptor. It also specifically inhibits the IL-2 driven cell proliferation in TS1 beta cells. These observations have lead to the hypothesis that its epitope is related to an IL-2 area involved in binding with IL-2R beta chain. This epitope was identified using various peptides covering the N-terminal half (including alpha helix A) of the 133 amino acids of IL-2. MAb 19B11/beta does not recognize peptides 30-54 and 44-54 but recognizes peptides 1-22 and 1-30 with a good affinity. Furthermore, threonine in position no. 3 was found to be critical for the binding of mAb 19B11/beta. A relationship between the epitope of mAb 19B11/beta and the glycosylation of the IL-2 molecule was observed. This further demonstrates that the NH2 terminal area of IL-2 is critical for IL-2/IL-2R beta interactions. Two other mAbs were studied during the course of this work. They served as control for the study of mAb 19B11/beta and provide some additional insight concerning the question of IL-2/IL-2R structure-function. MAb 16F11/alpha selectively blocks the IL-2 binding to TS1 alpha cells. The epitope of mAb 16F11 is conformational and it was not possible to study the corresponding IL-2/IL-2R alpha region of interaction. Epitope of mAb 3H9 is localized between residues 30 and 54 and does not affect the binding of IL-2 to IL-2R alpha.
Unité d'Immunogénétique Cellulaire, Institut Pasteur, Paris, France.
J L
JL
Moreau
M
M
Bossus
D
D
de Groote
C
C
François
Y
Y
Jacques
A
A
Tartar
J
J
Thèze
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000494:pharmacology; D000915:Antibody Affinity; D000918:Antibody Specificity; D001666:Binding Sites, Antibody; D001667:Binding, Competitive / Q000276:immunology; D002460:Cell Line; D004220:Disulfides / Q000494:pharmacology; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000737:chemistry / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D015375:Receptors, Interleukin-2 / Q000276:immunology / Q000378:metabolism*; D013912:Threonine / Q000737:chemistry
D000911:Antibodies, Monoclonal; D004220:Disulfides; D000939:Epitopes; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D013912:Threonine