Characterization of mouse interleukin‐12 p40 homodimer binding to the interleukin‐12 receptor subunits
X Wang, VL Wilkinson, FJ Podlaski… - European journal of …, 1999 - Wiley Online Library
X Wang, VL Wilkinson, FJ Podlaski, C Wu, AS Stern, DH Presky, J Magram
European journal of immunology, 1999•Wiley Online LibraryAbstract Interleukin‐12 (IL‐12) is a heterodimeric cytokine composed of two disulfide‐
bonded subunits, p35 and p40, which has important regulatory effects on T cells and natural
killer (NK) cells. In contrast to heterodimeric IL‐12, a homodimer of the p40 subunit,
designated (p40) 2, has been shown to be a potent IL‐12 antagonist. To study the
interaction between (p40) 2 and the known IL‐12 receptor (IL‐12R) subunits, IL‐12Rβ1 and
IL‐12Rβ2, we directly measured the binding activity of mouse (p40) 2 to ConA‐activated …
bonded subunits, p35 and p40, which has important regulatory effects on T cells and natural
killer (NK) cells. In contrast to heterodimeric IL‐12, a homodimer of the p40 subunit,
designated (p40) 2, has been shown to be a potent IL‐12 antagonist. To study the
interaction between (p40) 2 and the known IL‐12 receptor (IL‐12R) subunits, IL‐12Rβ1 and
IL‐12Rβ2, we directly measured the binding activity of mouse (p40) 2 to ConA‐activated …
Abstract
Interleukin‐12 (IL‐12) is a heterodimeric cytokine composed of two disulfide‐bonded subunits, p35 and p40, which has important regulatory effects on T cells and natural killer (NK) cells. In contrast to heterodimeric IL‐12, a homodimer of the p40 subunit, designated (p40)2, has been shown to be a potent IL‐12 antagonist. To study the interaction between (p40)2 and the known IL‐12 receptor (IL‐12R) subunits, IL‐12Rβ1 and IL‐12Rβ2, we directly measured the binding activity of mouse (p40)2 to ConA‐activated lymphoblasts and purified B cells from splenocytes of C57BL/6J mice. These results demonstrated the presence of both high (Kd about 5 pM) and low affinity (Kd about 15 nM) binding sites for mouse 125I‐labeled (p40)2. To elucidate which of the IL‐12R subunits binds mouse (p40)2, binding studies of mouse 125I‐labeled (p40)2 to Ba/F3 cells expressing recombinant mouse IL‐12Rβ1 and/or mouse IL‐12Rβ2 were carried out. Mouse IL‐12Rβ1 bound mouse 125I‐labeled (p40)2 with high and low affinities, comparable to that observed on Con A blasts and B cells. In contrast, mouse IL‐12Rβ2 bound mouse 125I‐labeled (p40)2 very poorly. These data demonstrate that similar to IL‐12, mouse (p40)2 binds with both high and low affinity to Con A blasts and B cells, and that IL‐12Rβ1 is responsible for mediating the specific binding of mouse (p40)2.
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