[The immunological profile of children with Down's syndrome]

In 1965 Benda demonstrated that bioptic and autoptic material of children with Down's syndrome showed hypoplasia of the thymus with poor histological differentiation between the cortex and medulla and impairment of Hassal's corpuscles which were also fewer than normal. In the seventies studies revealed the increased susceptibility to infections and higher incidence of leucosis in Down's syndrome patients as well as changes of immunologic defences (in particular cell mediated immunity). This study examines 35 children (16 boys and 19 girls) aged 6 months-20 years. Subjects were divided into a group of 18 cases in poor health with a history of recurrent infections and a group of 17 children in good health. Skin tests were performed by inoculating 0.1 ml of a solution formed by 1 ml physiological solution and 0.1 ml tetanus toxoid. Skin reaction was evaluated 48 hours later. Lymphocyte typing tests were performed with the rosette method and with monoclonal antibodies for T lymphocytes and with the determination of surface immunoglobulins for B lymphocytes. OKT4 (T helper), OKT8 (T suppressor) subsets assayed and the OKT4/OKT8 ratio was determined. Skin tests were negative in 3 cases (8.6%). The number of B lymphocytes was normal in all children. Total number of lymphocytes was decreased in 51.4% of cases. Two subjects had a reduction of OKT4 and 14 had an increased of OKT8 and 16 a significantly lower OKT4/OKT8 ratio. It is clear that skin tests were normal also in those children with low total lymphocyte values. The most closely related parameter to mobility was the OKT4/OKT8 ratio and the most distantly related on was the skin test. Only 3 cases had modifications of all 3 parameters together. Apart from the constant and complete immunological deficit described by many authors and which we cannot confirm the results of this study are in agreement with those of other authors.