An antibody to a 17 amino acid synthetic peptide of the type I interleukin-1 receptor preferentially blocks interleukin-1 beta binding.
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.
Clark
B D
BD
Department of Medicine, Tufts University School of Medicine, Boston, MA, USA.
Ikejima
T
T
Mancilla
J
J
Orencole
S F
SF
Sirko
S P
SP
Ishii
N
N
Okuda
K
K
Dinarello
C A
CA
D000595:Amino Acid Sequence; D000818:Animals; D000937:Antigen-Antibody Reactions; D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry; D007375:Interleukin-1 / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000276:immunology*; D011233:Precipitin Tests; D017433:Protein Structure, Secondary; D017472:Receptors, Interleukin-1 / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D012995:Solubility; D014407:Tumor Cells, Cultured; D014867:Water / Q000737:chemistry
D007136:Immunoglobulins; D007375:Interleukin-1; D010446:Peptide Fragments; D017472:Receptors, Interleukin-1; D014867:Water