In vitro cytotoxicity of lymphocytes from patients with "acquired" and sex-linked agammaglobulinaemia.

The in vitro cytotoxicity for fowl erythrocytes of circulating lymphocytes from nine patients with `acquired' and three patients with sex-linked agammaglobulinaemia was tested by release of sodium chromate (51Cr) after 42 hr of culture in the presence of phytohaemagglutinin (PHA). The lymphocyte cytotoxicity of three patients with `acquired' agammaglobulinaemia was low, but that of the other six and of the three patients with sex-linked agammaglobulinaemia were normal. All the `acquired' agammaglobulinaemic patients had markedly diminished thymidine uptake in response to PHA at 3 days, but a normal response at 7–10 days, but the three boys with sex-linked agammaglobulinaemia showed a normal response. The findings further demonstrate the heterogeneity of lymphocyte abnormalities in patients with agammaglobulinaemia.