Induction of antiphospholipid antibodies by immunization with synthetic viral and bacterial peptides

We previously induced pathogenic antibodies against anionic phospholipids ( PL) in experimental animals by immunization with lipid-free purified human beta(2)glycoprotein I (beta(2)GPI). We hypothesized that antiphospholipid a ntibodies (aPL) are induced by in vivo binding of foreign beta(2)GPI to sel f-FL, thus forming an immunogenic complex against which aPL antibodies are produced. If this hypothesis is true, other PL-binding proteins that are pr oducts of ubiquitous viral/bacterial agents may also induce aPL. To test th is hypothesis, groups of NIH/Swiss mice were immunized with synthetic pepti des of viral and bacterial origin that share structural similarity with the putative PL-binding region of beta(2)GPI. Compared with the control groups , animals immunized with the peptides produced significantly higher levels of aPL and anti-beta(2)GPI antibodies. These findings demonstrate that some PL-binding viral and bacterial proteins function like beta(2)GPI in induci ng aPL and anti-beta(2)GPI production, and are consistent with a role for s uch viral and bacterial proteins in inducing aPL antibody production in hum ans.