Abstract
BackgroundDown syndrome (DS) is the most common and best-known chromosomal disorder and is associated with several other pathologic conditions including immunodeficiency which makes a significant contribution to morbidity and mortality. Various immunological theories and observations to explain the predisposition of individuals with DS to various infections have been published, one of which is increased apoptotic cells.AimThe aim of this study was to identify the effect of apoptosis on both types of cells of specific immune response (T and B lymphocytes) in children with DS using Annexin V staining of phosphatidyserine (PS) as a specific marker of early apoptosis.Subjects and methodsThe study included 17 children with karyotypically ascertained DS (7 males and 10 females). Their ages ranged from 4 months to 14 years with mean age of 5.7 ± 4.35 years. Seventeen age and sex matched healthy children were included in the study as controls. Patients or controls with infections were excluded from the study. Complete blood picture, immunophenotyping, analysis of apoptosis using Annexin V was done at National cancer Institute to all children included in this study.ResultsAlthough CBC, differential count, relative and absolute number of CD3+ and CD16+ did not show significant differences between DS children and control group, the relative and the absolute size of apoptotic CD3+ T lymphocytes, and the relative size of apoptotic CD19+ B lymphocytes were significantly higher in DS children than in controls. On the other hand, no significant difference was detected as regards the absolute size of CD19+ B lymphocytes in DS children and in controlsConclusionour finding of increased early apoptotic cells (especially T cells) in DS children may emphasize the fact that the function of cells- and not their number- is main mechanism responsible for the impairment of the immune system in DS children and may further add to the known fact that cellular immunity is more severely affected than humoral immunity in these children. Further studies on apoptotic cellular phenotype in larger number of DS are needed
Highlights
Down syndrome (DS) is the most common and bestknown chromosomal disorder
CBC, differential count, relative and absolute number of CD3+ and CD16+ did not show significant differences between DS children and control group, the relative and the absolute size of apoptotic CD3+ T lymphocytes, and the relative size of apoptotic CD19+ B lymphocytes were significantly higher in DS children than in controls
No significant difference was detected as regards the absolute size of CD19+ B lymphocytes in DS children and in controls
Summary
Down syndrome (DS) is the most common and bestknown chromosomal disorder It is associated with several pathologic conditions including immunodeficiency which makes a significant contribution to morbidity and mortality in these children. Previous authors reported increased apoptotic cells in neurons and granulocytes of DS patients [8,9] It has been studied in the peripheral blood by means of electron microcopy, in situ nick translation (ISNT) and DNA electrophoresis [10]. Apoptosis can be detected using Annexin V staining of phosphatidyserine (PS) This method has been used before by Corsi et al, 2003 who reported an increase in early apoptotic CD3 lymphocytes in DS children compared to the controls [11]. Various immunological theories and observations to explain the predisposition of individuals with DS to various infections have been published, one of which is increased apoptotic cells
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