INHIBITION OF INTERLEUKIN-2 P55 RECEPTOR SUBUNIT INTERACTION BY COMPLEMENTARY PEPTIDES/

Complementary peptides to interleukin-a (IL-2) sequences important for receptor binding were tested for their ability to mimic natural recep tors and act as inhibitors of the IL-2/p55 receptor subunit interactio n. Peptides hydropathically complementary to IL-2 sequences 15-27 and 40-54 were synthesized in a linear and in a multimeric form and then c haracterized first by solid-phase binding assays for their ability to interact with IL-2. Binding between the multimeric complementary pepti des and biotinylated IL-2 was specific, saturable, and inhibited by li near as well as multimeric complementary peptides, Saturable interacti ons, characterized by dissociation constants in the micromolar range, occurred also between IL-2 immobilized on microtiter plates and biotin ylated linear and multimeric complementary peptides, Peptides correspo nding to the IL-2 target sequences were able to interfere with this in teraction, as well as full-length IL-2. Peptide recognition was sequen ce dependent, since scrambling of complementary peptide sequences or I L-2 target peptide sequences abolished binding, Multimeric complementa ry peptides after immobilization on solid supports proved useful also for affinity purifications of recombinant IL-2 or IL-2 fragments corre sponding to the target sites, directly from crude mixtures, in high yi eld and with high recovery. Complementary peptides to IL-2 sequence 15 -27, but not to IL-2 sequence 40-54, in the linear or in the multimeri c form, even if with different potency, interfered with the IL-2/p55 r eceptor subunit interaction in vitro, thus suggesting a possible role of this IL-2 site in receptor recognition. (C) 1995 Academic Press,Inc .