title: Abnormal in vitro thymocyte differentiation in a patient with severe combined immunodeficiency-Nezelof's syndrome.
abstract: An in vitro coculture model system of CD34+ stem cells and allogenic cultured thymic epithelia fragments was used to evaluate thymocyte differentiation in a 9-month-old child of Amish descent with Nezelof syndrome. Though the patient's stem cells differentiate to acquire normal expression of CD2 and CD7, later steps of maturation were abnormal. There was detectable but reduced expression of CD3 and CD4 phenotypes. CD44+ expression, however, was markedly reduced. CD44 is an adhesion molecule, interacting with the matrix ligands hyaluronan and fibronectin, and is expressed early in thymocyte differentiation and subsequently in mature T cells. It is hypothesized that abnormal expression of CD44 in a variant of severe combined immunodeficiency, Nezelof's syndrome, interferes with normal thymocyte and thymic epithelial interaction, which leads to abnormal thymocyte differentiation.
authors: Department of Pediatrics, St. Louis University Health Sciences Center, Missouri 63110, USA.
authors: A P
authors: AP
authors: Knutsen
authors: D
authors: D
authors: Wall
authors: K R
authors: KR
authors: Mueller
authors: J D
authors: JD
authors: Bouhasin
mesh_terms: D018952:Antigens, CD34 / Q000096:biosynthesis; D002454:Cell Differentiation / Q000276:immunology; D018920:Coculture Techniques; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000276:immunology; D006801:Humans; D007223:Infant; D008297:Male; D016511:Severe Combined Immunodeficiency / Q000276:immunology* / Q000473:pathology*; D013601:T-Lymphocytes / Q000473:pathology*; D013950:Thymus Gland / Q000276:immunology / Q000473:pathology*
chemical_list: D018952:Antigens, CD34