Australia antigen, autoantibodies and cell-mediated immune responses in patients with Down's syndrome.

The prevalence of Au antigen, autoantibodies and impaired cell-mediated immune responses was studied in 66 patients with Down's sydrome and 66 other mentally retarded patients in a South Australian institution. The antigen was detected in three of the former and none of the latter. This unexpectedly low carrier rate in patients with Down's syndrome was thought to be due either to good hygiene and state of nutrition in the institution or to the high age of which the patients had been admitted to hospital (eight to nine years). Because of the incompleteness of the association between impairment of cell-mediated immunity and antigen carriage, it was thought unlikely that the former was the sole reason for the latter.