Intravenous immune globulin (
IVIG) is now under evaluation for the treatment of patients with the forms of
systemic vasculitis associated with
anti-neutrophil cytoplasmic antibodies (
ANCA). Although
IVIG may produce effects by a variety of mechanisms, including control of T-cell function, interference with
cytokine action, and
Fc receptor blockade, it is the regulation of
autoantibody production by B cells, through idiotypic-anti-idiotypic reactions, that makes this treatment attractive for patients with
systemic vasculitis. The author and others have shown the importance of
ANCA idiotypic-anti-idiotypic reactions in vitro and demonstrated that these could be influenced by anti-idiotypic determinants present in
IVIG. Thus F(ab')2 fragments of
IVIG could block
ANCA binding to
antigen, in a dose-dependent fashion. The degree of inhibition was variable, ranging up to 100% for the
ANCA-containing sera of certain patients. Similar inhibitory activity could be found in the sera of patients in remission
after treatment, as well as in occasional patients whose disease remitted spontaneously, without drugs being used. Thus,
IVIG appears to be particularly valuable in the management of
vasculitis in the elderly, the very young and for pregnant women, as well as for those at any age who are vulnerable to
infection.