Immunoregulatory CD4+ CD45R+ suppressor/inducer T lymphocyte subsetsand impaired cell-mediated immunity in patients with Down's syndrome

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Abstract
SUMMARY: The monoclonal antibodies 2H4 and 4B4 allow CD4+ and CD8+ T lymphocytes to be subdividedinto CD45R+ and CDW29+ functional subpopulations. The CD4+ CD45R+ lymphocytes aredesignated as suppressor/inducer and CD4+ CDW29+ as helper/inducer subsets. Peripheral bloodlymphocytes from 19 patients with Down's syndrome and 19 age- and sex-matched normal controlswere analysed for the CD45R+ and CDW29+ subsets from the CD4+ and CD8+ T lymphocytes. Thepercentage of CD4+ CD45R+ cells (suppressor inducer) was markedly increased and of CD4+CDW29+ cells (helper/inducer) decreased in all patients with Down's syndrome. In contract, thepercentage of CD8+ CD45R+ and CD8+ CDW29+ subsets showed no major differences betweenpatients with Down's syndrome and normal controls. Moreover, an alteration in the CD4+ andCD45R+ and CD4+ CDW29+ T cell subsets was accompanied by a markedly reduced proliferativeresponse to phytohaemagglutinin and concanavalin A stimulation of the CD4+ T lymphocytes. Thus, a deficiency exists in patients with Down's syndrome in the CD4+ CDW29+ helper/inducerT cell subset which may contribute to their impaired cell-mediated immunity.