A once obscure medical treatment is seeing new popularity thanks
to an improved understanding of the role the immune system plays
in conditions as varied as obsessive-compulsive disorder (OCD)
and Alzheimer's disease. Some worry that supplies of intravenous
immunoglobulin (IVIG), which is made of blood plasma from
donors, may run short if a clinical trial confirms its
effectiveness at slowing the progress of Alzheimer's. IVIG
contains an antibody known as IgG that helps to ward off
infection, modulates the immune system and reduces inflammation,
although the full extent of how IVIG works remains unknown. When
IVIG was first approved commercially in the early 1980s—it was
prescribed to replace antibodies in patients with primary
immunodeficiency disease (PIDD) and, later, was used to regulate
the immune system in autoimmune conditions such as multiple
sclerosis. Today IVIG has over 100 off-label indications, which
represent the fastest-growing sector of its market. Among these
are an emerging crop of psychiatr