Lymphocyte surface markers and serum immunoglobulins in persons with Down's syndrome.

Distributions of the serum immunoglobulins, of T and B lymphocytes, and subpopulations of B lymphocytes were studied in children and institutionalized adults with Down's syndrome and appropriate mentally retarded controls. Noninstitutionalized Down's syndrome children, who were 2 to 6 years of age, had lower serum IgM levels, lower total white blood cell counts, lower total lymphocytes, lower B lymphocytes, and lower IgM- and IgA-producing lymphocytes than did retarded controls. Institutionalized Down's syndrome adults, 17 to 51 years of age, had significantly higher serum IgG and IgA levels than did retarded controls. Their total lymphocytes, B lymphocytes, and IgM-producing lymphocytes were in the same direction as in the Down's syndrome children but were of borderline statistical significance (between p = .09 and .11). T lymphocytes were not significantly lower for any of the Down's syndrome-retarded groups than those for controls, but the trend was in that direction.