title: Down's syndrome: problems of immunodeficiency.
abstract: The high susceptibility to infections, malignancies, and autoimmune disorders of subjects with Down's syndrome (DS) is associated with laboratory and pathological evidence of immunodeficiency. The percentage of circulating T-lymphocytes is indeed low from birth, and lymphocyte proliferative response to mitogens, normal during the 1st decade of life, declines rapidly thereafter. There is indirect evidence that T-lymphocyte maturation is impaired in DS; furthermore, the thymus is morphologically deranged and there is recent direct evidence that serum levels of thymic hormones are low. It is suggested that the immunodeficiency of DS results from a defect limited primarily to the epithelial cells of the thymus which fail to synthesize or secrete one or more hormones necessary for the differentiation of T-lymphocytes.
mesh_terms: D000293:Adolescent; D000328:Adult; D002454:Cell Differentiation; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000150:complications* / Q000276:immunology; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000150:complications* / Q000209:etiology / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008213:Lymphocyte Activation; D008875:Middle Aged; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology