[Humoral immunity and blastic transformation of lymphocytes in trisomy 21].

Studies of immunologic parameters in 52 children with trisomy 21 revealed that -the changes in serum immunoglobulin patterns were minimal, although some delay in the age-dependent rise of IgG concentration was observed; -lymphocyte reactivity to phytohemagglutinin showed a shift with maximal 3H-thymidine incorporation at low PHA concentration; -presence of HBs antigen at an increased incidence, possible existence of anti-thyroid antibodies in serum of trisomy patients and also in that of their parents, abnormalities in phagocytosis, illustrate that trisomy 21 can be associated with multiple immunologic dysfunctions.