T and B lymphocytes in patients with Down's syndrome.

Individuals with Down's syndrome are thought to have abnormalities of immune function. Studies to quantify the number of peripheral blood T and B lymphocytes and serum immunoglobulins in 12 individuals and 12 sex and age matched control subjects were performed. Hepatitis B antigen and antihyroglobulin antibodies as markers of possible immune dysfunction were determined. The numbers of circulating T and B cells, and the level of serum immunoglobulins in children with Down's syndrome did not differ from nonretarded control children. Circulating hepatitis B antigen and antihyroglobulin antibodies were not present. These studies indicated that quantitative abnormalities of T and B cells are not present in children with Down's syndrome. The data did not exclude the existence of qualitative abnormalities.