Quantified deficiency of lymphocyte response to phytohaemagglutinin in immune deficiency diseases.

Using a quantitative assay of lymphocyte responsiveness to different concentrations of phytohaemagglutinin (PHA), it has been possible to demonstrate that the lymphocytes of children with ataxia telangiectasia do not respond normally. The response to PHA is nearer normal at higher concentrations of PHA. In the same system, it has been shown that although the lymphocytes of children with probable infantile sex-linked agammaglobulinaemia (Bruton's disease) may respond normally at higher concentrations of PHA, at lower concentrations their response is subnormal. The results reported indicate that if lymphocyte response to PHA is defective in an immune deficiency disease, then the response at lower concentrations of PHA provides the most sensitive discriminatory information.