Studies of lymphocyte function in patients with Down's syndrome

Abstract

A defective immune response has been suspected in patients with Down's syndrome because of persistent reports of increased susceptibility to infection, high incidence of leukemia early in childhood, high and persistent levels of Australia antigen, and reports of differences in distribution of plasma immunoglobulins among the various classes. In this study, noninstitutionalized patients with Down's syndrome between the ages of 6 and 18 years were compared to youngsters of the same age and sex with normal chromosome karyotypes. Significant differences were found in the distribution of plasma immunoglobulins between classes, although the total amount of immunoglobulins was not significantly different in the two groups. Peripheral lymphocytes were isolated from venous blood using centrifugation in discontinuous gradients of sodium metrizoate. Stimulation of lymphocytes from patients with Down's syndrome by phytohemagglutinin or pokeweed mitogen resulted in fewer cells undergoing blast transformation, although the time course was similar to controls. Aminoisobutyric acid and 3 O methylglucose uptake was stimulated to a lesser extent in Down's syndrome lymphocytes by phytohemagglutinin while calcium uptake was higher. In response to standardized stimulation by pokeweed mitogen, venous lymphocytes from Down's patients synthesized fewer immunoglobulins in vitro than lymphocytes from controls.