The present invention provides domain 1 .beta..sub.2 GPI polypeptides,
polynucleotides encoding these polypeptides, mimetics of these
polypeptides, and methods using domain 1 .beta..sub.2 GPI polypeptides and
mimetics. Domain 1 of .beta..sub.2 GPI has been shown to bind to
anti-cardiolipin (.beta..sub.2 GPI-dependent antiphospholipid) antibodies,
which are associated with several pathologies, such as thrombosis and
fetal loss. The domain 1 .beta..sub.2 GPI polypeptides may be used to
detect .beta..sub.2 GPI-dependent antiphospholipid antibodies in a sample.
The invention further provides methods of inducing tolerance using these
domain 1 .beta..sub.2 GPI polypeptides.
