title: Age-related alterations of the CD19 complex and memory B cells in children with Down syndrome.
abstract: Children with Down syndrome (DS) have a high incidence of recurrent respiratory tract infections, leukaemia and autoimmune disorders, suggesting immune dysfunction. The present study evaluated the role of the CD19 complex and memory B cells in the pathogenesis of immunodeficiency in children with DS. The expression levels (median fluorescein intensity-MFI) of CD19, CD21 and CD81 molecules on the surface of B cells and memory B cell subsets were studied in 37 patients and 39 healthy controls. Twenty-nine of the DS group had congenital cardiac disease. The B cell count was significantly low in children with DS compared with healthy age-matched controls for all three age groups (under 2 years; 2-6 years and older than 6 years). The MFI of CD19 was reduced in all the age groups, whereas that of CD21 was increased in those older than 2 years with DS. The expression level of CD81 was significantly increased in those older than 6 years. Age-related changes were also detected in memory B cell subsets. The frequency of CD27+IgD+IgM+natural effector B cells was reduced in children with DS who had needed hospitalisation admission due to infections. The observed intrinsic defects in B cells may be responsible for the increased susceptibility of children with DS to severe respiratory tract infections.
authors.affiliation: Department of Pediatric Immunology and Allergy, Selcuk University Medical Faculty, Alaeddin Keykubat Kampusu, 42131, Konya, Turkey.
authors.forename: Ayse Nazli
authors.initials: AN
authors.lastname: Seckin
authors.affiliation: Department of Pediatric Immunology and Allergy, Selcuk University Medical Faculty, Alaeddin Keykubat Kampusu, 42131, Konya, Turkey.
authors.forename: Hulya
authors.initials: H
authors.lastname: Ozdemir
authors.affiliation: Department of Pediatric Immunology and Allergy, Selcuk University Medical Faculty, Alaeddin Keykubat Kampusu, 42131, Konya, Turkey.
authors.forename: Ayca
authors.initials: A
authors.lastname: Ceylan
authors.affiliation: Department of Pediatric Immunology and Allergy, Selcuk University Medical Faculty, Alaeddin Keykubat Kampusu, 42131, Konya, Turkey. hasibeartac@yahoo.com.
authors.forename: Hasibe
authors.initials: H
authors.lastname: Artac
mesh_terms: D000293:Adolescent; D000367:Age Factors; D018941:Antigens, CD19 / Q000032:analysis*; D001402:B-Lymphocytes / Q000737:chemistry* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000473:pathology*; D005260:Female; D006801:Humans; D007156:Immunologic Memory; D007223:Infant; D018655:Lymphocyte Count; D008231:Lymphopenia; D008297:Male; D011446:Prospective Studies; D017464:Receptors, Complement 3d / Q000032:analysis; D060225:Tetraspanin 28 / Q000032:analysis
chemical_list: D018941:Antigens, CD19; C000604811:CD19 molecule, human; C554798:CD81 protein, human; D017464:Receptors, Complement 3d; D060225:Tetraspanin 28
keywords: CD19 complex; Down syndrome; Memory B cells