Synthetic peptides mapping to epitopes of the extracellular domain of the interleukin-2 receptor beta-chain to inhibit T-cell activation.
Expression of the high-affinity IL-2 receptor (IL-2R) on the surface of activated T cells makes it an attractive target for selective inhibition of alloreactive T cells in organ transplantation. IL-2 binds to its receptor via the extracellular domain of the beta-chain. In this study we synthesized synthetic peptides that map to epitopes of this domain and tested their ability to inhibit the activation and proliferation of mitogen-stimulated peripheral-blood T cells. Solid-phase synthesis was applied to create three oligopeptides of primary structures corresponding to the epitopes M(107)-E(118), Y(178)-Q(199), and E(190)-Q(199) of the extracellular domain of the IL-2Rbeta-chain. A nonhomologous peptide served as control. Peripheral-blood mononuclear cells isolated from 16 healthy volunteers (median age 41 years, range 26 to 56 years) were cultured with various concentrations of peptides and the mitogen phytohemagglutinin (PHA). The inhibitory effect of the peptides on cell proliferation was evaluated by automated cell counting and colorimetric proliferation assays. Cell activation was assessed by immunophenotyping using antibodies directed toward CD4, CD25, or CD69. The amount of IL-2 in culture supernates was measured by enzyme-linked immunoassay. Cultures in the presence of the peptide M(107)-E(118) (500 nmol/L) inhibited PHA-induced T-cell proliferation by 38%, and IL-2 secretion by 57%. Immunophenotyping confirmed suppression of activated T cells. Peptides Y(178)-Q(199) and E(190)-Q(199) inhibited proliferation, but failed to significantly affect IL-2 secretion. The control peptide showed no effect on the activation parameters. Our data indicate that the M(107)-E(118) peptide has promise for organ transplantation therapy.
Parissi
T
T
Laboratory of Hematology & Transfusion Medicine, Medical School, University of Patras, Greece.
Chatzantoni
K
K
Deraos
S
S
Matsoukas
I
I
Mouzaki
A
A
D000328:Adult; D000595:Amino Acid Sequence; D001782:Blood Donors; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D006801:Humans; D016130:Immunophenotyping; D053646:Interleukin-2 Receptor beta Subunit; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology / Q000494:pharmacology*; D010449:Peptide Mapping; D018123:Receptors, Interleukin / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D000939:Epitopes; C508020:IL2RB protein, human; D053646:Interleukin-2 Receptor beta Subunit; D010446:Peptide Fragments; D018123:Receptors, Interleukin