Regulation of autoreactivity by the idiotypic network and therapeutic modulation of autoimmunity by polyvalent intravenous immunoglobulins (IgIV).

A beneficial effect intravenous administration of immunoglobulins (IgV) has been reported in a large number of autoimmune disease, whether mediated by autoantibodies or T cells. The short-term immunoregulator effect for IgV, mediated by interaction of the Fc fragment of the immunoglobulins with the Fc receptors on the surface of leukocytes has been thoroughly described. The arguments presented in this review indicate that one of the consequences of IgV administration is to restore regulation of autoreactivity via a network of interactions between ''natural'' autoreactive IgG in the infusion and elements of the immune system. Via this network, IgIB can i) produce transient or long-term suppression of specific autoreactive clones and stimulation of reactive B cells with IgIV fragments F(ab); ii) restore normal fluctuations in natural autoantibody titre in the serum; and iii) modulate synthesis of cytokine secretion.