DNA polymerase activity as an index of lymphocyte stimulation: studies in Down's syndrome.

The ability of peripheral blood lymphocytes to respond to phytohemagglutinin (PHA) in vitro was studied in patients with Down's syndrome. The response was measured by the increase in DNA polymerase activity and the rate of incorporation of tritiated thymidine by the cultured lymphocytes. These activities were significantly lower in PHA-stimulated lymphocytes from patients with Down's syndrome compared with age- and sex-matched, mentally retarded patients without Down's syndrome from the same institution and the normal healthy volunteers.

Hepatitis and Australia antigen: autosomal recessive inheritance of susceptibility to infection in humans.

Examples of inherited susceptibility to infection controlled by genes segregating at one or a small number of loci have been identified in lower animals. In this study we report data on what appears to be a similar situation in humans. "Australia antigen" is an antigen found in the sera of patients with acute and chronic hepatitis, and it may actually be a form of virus.