Immunochemical characterization of antigenic domains on human IL-2: spatially distinct epitopes are associated with binding to the p55 and p70 subunits of IL-2 receptor.
We have isolated and characterized 8 mAb against human rIL-2. All recognize nonglycosylated rIL-2 in liquid phase with similar affinities (Kd approximately 1 nM). Based on the epitopes of the IL-2 molecule that they recognize and their pattern of reactivity against glycosylated and non-glycosylated IL-2, they have been classified into four groups. The first group of anti-IL-2 mAb (2C4, 19B11 and 12C2) inhibits IL-2 binding to p70 IL-2R, while the second one (16F11, 18E1 and 2A4) prevents its binding to p55 IL-2R. These two groups neutralize IL-2 activity in a T cell proliferation assay equally well, due to their similar inhibition of IL-2 binding to high affinity IL-2R. Two mAb, 3H9 and 17F4, recognize separate epitopes on IL-2 molecule, are poor inhibitors of IL-2 binding, and they are inefficient in the neutralization of its biological activity; they have been assigned to the third and fourth groups, respectively. These results show that mAb from the first and second group recognize two epitopes of the human IL-2 molecule which probably overlap the p70 IL-2R and p55 IL-2R binding sites, respectively. In addition, these areas together form the high affinity IL-2R binding site. The two mAb from the third and fourth group recognized epitopes of IL-2 not directly involved in IL-2 binding to its receptor. All eight mAb anti-human IL-2 recognize murine IL-2 and with the exception of one, 17F4 mAb are also able to neutralize it in a T cell proliferation assay. The relationship between the structure and the function of the IL-2 molecule is discussed.
Unité d'Immunogénétique Cellulaire, Institut Pasteur, Paris, France.
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A
Rebollo
D
D
De Groote
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M
Baudrihay
J
J
Thèze
D L
DL
Jankovic
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D002478:Cells, Cultured; D000939:Epitopes; D006031:Glycosylation; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D011994:Recombinant Proteins / Q000276:immunology; D013045:Species Specificity
D000911:Antibodies, Monoclonal; D000939:Epitopes; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins