Sir.—Spina et al (Journal 1981; 135:251-255) reported a study of immune function in Down's syndrome (DS), which showed markedly reduced B-lymphocyte and altered T-lymphocyte proliferative response to phytohemagglutinin (PHA). They suggested that the anomalies in DS immune function are similar to those found in aged normal subjects and may be the result from common environmental factors, such as exposure to infectious agents.
The influence of aging on immune function in DS, a fact well documented in recent literature (as Spina et al showed) moved us to study the possible immunological early defect in DS.
Forty-six children with DS, aged 12 to 46 months, noninstitutionalized, and without concurrent diseases, were tested.
Assessments were performed twice with a two-month interval, and results compared with 20 agematched, healthy control subjects. Our results, reported elsewhere,1 showed a normal humoral immunity in DS in infancy, with normal serum immunoglobulins and B cells (expressed both