ANTIIDIOTYPES AGAINST ANTIPHOSPHOLIPID ANTIBODIES ARE PRESENT IN NORMAL POLYSPECIFIC IMMUNOGLOBULINS FOR THERAPEUTIC USE

In the present study we found that antiphospholipid activity in sera f rom patients with anticardiolipin antibodies was inhibited in vitro by therapeutic polyspecific normal immunoglobulins (IVIg). In fact, F(ab '), fragments from IVIg (IVIg-F(ab')2) inhibited the binding of antica rdiolipin antibodies to the corresponding antigen in a dose-dependent fashion, thus suggesting that the interaction between IVIg-F(ab'), and anticardiolipin antibodies occurred within or near the antigen combin ing site. The maximal inhibition ranged from 35.25 +/- 5.56 to 64 +/- 5.48%. In addition, patients' IgG containing antiphospholipid activity specifically bound insolubilized IVIg-F(ab')2, as assessed by enzyme- linked immunosorbent assay (ELISA). These results indicate that IVIg o btained from a large pool of normal donors contain anti-idiotypic anti bodies directed against idiotypes located on antiphospholipid antibodi es. Moreover, our observations suggest that the reported favourable ef fect of high dose infusion of IVIg in patients with recurrent abortion s due to antiphospholipid antibodies may depend, at least in part on i nhibition of the binding of such autoantibodies to the corresponding a ntigens (s) and/or inactivation of idiotype bearing B cell clones.