Multivalent thioether-peptide conjugates: B cell tolerance of an anti-peptide immune response

Antibodies which bind beta(2)-glycoprotein I (beta(2)GPI) are associated wi th antiphospholipid syndrome. Synthetic peptide mimotopes have been discove red which compete with beta(2)GPI for binding to selected anti-beta(2)GPI. A thiol-containing linker was attached to the N-terminus of two cyclic thio ether peptide mimotopes, peptides 1a and 1b. The resulting peptides, with l inker attached, were reacted with two different haloacetylated platforms to prepare four tetravalent peptide-platform conjugates to be tested as B cel l toleragens. The linker-containing peptides were reacted with maleimide-de rivatized keyhole limpet hemocyanin (KLH) to provide peptide-KLH conjugates . Peptides 1a and 1b were also modified by acylation with 3-(4'-hydroxyphen yl)propionic acid N-hydroxysuccinimidyl ester. The resulting hydroxyphenyl peptides were radioiodinated and used to measure anti-peptide antibody leve ls. The KLH conjugates were used to immunize mice to generate an anti-pepti de immune response. The immunized mice were treated with the conjugates or saline solution and boosted with the appropriate peptide-KLH conjugate. Thr ee of the four conjugates suppressed the formation of anti-peptide antibody . The stabilities of the conjugates in mouse serum were measured, and the r elative stabilities did not correlate with ability to suppress antibody for mation.