Are antibasal ganglia antibodies important, and clinically useful?

In the last decade there has been controversy over the existence and clinical significance of autoantibodies that react with the basal ganglia, referred to as antibasal ganglia antibodies (ABGAs) (some investigators have referred to them as anti-neuronal antibodies). The spectrum of disorders associated with ABGAs has recently been widened to include several neuropsychiatric syndromes; in common is their association with recent streptococcal infection, which suggests that these syndromes are due to an aberrant immune response triggered by streptococcal infection. Like other emerging diseases it will take time to establish causation, if any, and for these disorders to be accepted as real disease entities. Because they may turn out to have a considerable clinical impact, they clearly need to be better understood, as does ABGA testing in clinical practice. ABGAs are autoantibodies that cross-react with human brain tissue, with the highest binding specificity against extracts from the caudate and putamen.1 They were originally detected using immunofluorescence microscopy (fig 1) in patients with Sydenham’s chorea,2 the prototypical post-streptococcal disease of the central nervous system (CNS). ABGAs can also be detected by Western blotting of an antigen preparation of human or rodent basal ganglia, or using enzyme-linked immunosorbent assays (ELISA).1 The sensitivity and specificity of the ELISA when using a crude antigen preparation is inferior to Western blotting.1 The performance of the ELISA may be improved in the future with the use of recombinant autoantigens.3 Figure 1 Immuofluorescence microscopy and Western blot of ABGAs. (A) Normal control diluted 1/50 tested against human basal ganglia with no specific staining (magnification ×200). (B) Sample from a patient with Sydenham’s chorea diluted 1/50 and tested against human basal ganglia tissue; IgG staining of axons (arrows) (magnification ×200). (C) Western blots showing serial dilution of strongly positive ABGAs in patients with post-streptococcal movement disorder. …