Lymphocytes in congenital immunological deficiency diseases.

The in vitro lymphocyte response to phytohaemagglutinin (PHA) and antigens was normal in five patients with Bruton-type agammaglobulinaemia. Lymphocytes from one infant with thymic dysplasia failed to respond to PHA. The response to PHA and antigens was variable in three patients with ataxia telangiectasia. The in vitro lymphocyte response in these patients appears to reflect the state of thymic-dependent cellular immunity or capacity for delayed hypersensitivity reactions. The in vitro lymphocyte response to PHA and antigens was normal in two children with Wiskott-Aldrich Syndrome, a disease in which the immunological defect remains controversial. Lymphocytes from a child who had been thymectomized at birth responded normally to PHA, and a normal capacity for delayed hypersensitivity reactions was demonstrated by skin test and homograft rejection.