1. An antibody to a 17 amino acid synthetic peptide of the type I interleukin-1 receptor preferentially blocks interleukin-1 beta binding.
- Author
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Clark BD, Ikejima T, Mancilla J, Orencole SF, Sirko SP, Ishii N, Okuda K, and Dinarello CA
- Subjects
- Amino Acid Sequence, Animals, Binding Sites, Cell Line, Humans, Immunoglobulins chemistry, Mice, Molecular Sequence Data, Molecular Weight, Precipitin Tests, Receptors, Interleukin-1 chemistry, Receptors, Interleukin-1 metabolism, Solubility, Tumor Cells, Cultured, Water chemistry, Antigen-Antibody Reactions, Interleukin-1 metabolism, Peptide Fragments immunology, Protein Structure, Secondary, Receptors, Interleukin-1 immunology
- Abstract
On the basis of their relative hydropathy and alpha-helical structure, we prepared antibodies to four synthetic peptides with amino acid sequences homolgous to four hydrophilic, extracellular regions of the murine 80 kDa type I interleukin-1 receptor (IL-1RI). Antibodies to each of the four peptides recognized their specific immunogen. Human [125I]-IL-1 alpha or -beta was crosslinked to murine EL4 and D10S cells. Antiserum to peptide 150-166 precipitated the IL-1/IL-1R complex, whereas antibodies to peptide 66-84, 190-200, or 266-285 did not. Antibody to peptide 150-166 did not precipitate the type II IL-1R. Anti-IL-1RI150-166 blocked 71% of the binding of radiolabeled human IL-1 beta to EL4 cells and 50% of the binding to D10S cells. Using affinity-purified anti-IL-1RI150-166, we compared the ability of this antibody to inhibit the binding of murine or human IL-1 alpha to that of murine or human IL-1 beta. At a concentration of 20 ng/ml, affinity-purified anti-IL-1RI150-166 blocked 50% binding of murine IL-1 beta. At 1 microgram/ml, 90% blockage was observed. In contrast, no significant blockade of IL-1 alpha binding was observed at concentrations as high as 3 micrograms/ml of anti-IL-1RI150-166. The selective blockade of IL-1 beta forms was not due to differences in the affinities of these ligands for receptors on these cells. The antibody also blocked the binding of human IL-1 beta but not human IL-1 alpha to EL4 cells. The biologic activity of murine IL-1 beta but not IL-1 alpha on EL4 cells was also inhibited by this antibody. These data suggest (1) that antibody to a specific epitope on the extracellular domain interferes with the binding of IL-1 beta but not IL-1 alpha, (2) the differential inhibition of binding of IL-1 beta but not IL-1 alpha by anti-IL-1RI150-166 also blocks biologic activity, and (3) IL-1 alpha and IL-1 beta may transduce different signals by binding to separate loci on the IL-1RI.
- Published
- 1996
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