Anti-idiotypic antibodies against anti-phospholipid autoantibodies which suppress lupus-like anticoagulant activity.

We have studied IgG F(ab')2 fractions in the plasma from a patient during spontaneous remission from lupus anticoagulant (LAC). Fractions from the remission period inhibited the LAC activity of preremission fractions, as evaluated by in vitro coagulation tests. Idiotypic/anti-idiotypic interactions were demonstrated by affinity chromatography. The same results were obtained with IgG F(ab')2 from pooled normal plasma. This enables us to treat the LAC relapse in this patient with purified recurrent anti-idiotypic determinant antibodies extracted from normal plasma.