Lymphocyte surface phenotypes in Down's syndrome.

The lymphocyte surface phenotypes in the blood of 7 non-institutionalized adults with trisomy-21, and in 10 karyotypically normal control subjects, were analysed by fluorescent microscopy with an OKT series of monoclonal antibodies. Whereas the proportions of OKT3+, OKT4+ and OKT6+ cells were similar in the two groups, the percentages of both OKT8+ and OKT10+ trisomic lymphocytes were significantly higher. The biological implications of these findings with respect to the underlying immunopathology of Down's syndrome are discussed.