Flow cytometric comparison of RNA content in peripheral blood mononuclear cells of down syndrome patients and control individuals

Abstract

Objective: Trisomy 21 or Down syndrome (DS) is the most common genetic cause of mental retardation associated with the immunologic and other known defects. Extra chromosome 21 of DS patients contains an average of 40 extra copies of rRNA genes and the in vivo regulation of these genes' activity is not known. Because over 80% of total cellular RNA is rRNA, the measurement of total cellular RNA provides information on rRNA content. The aim of this work was to determine whether or not the additional chromosome 21 causes any increase in total cellular RNA content in mononuclear cells from peripheral blood (PBMNCs) of these patients and whether or not this content is modified with age.Method: PBMNCs of 48 patients with DS and 48 healthy controls were studied. RNA content of isolated PBMNCs was evaluated by flow cytometric measurements.Results: Average RNA content of younger DS patients' cells was significantly higher than that of healthy controls (P = 0.003). Furthermore, the RNA content decreased significantly with increasing age of DS patients (r = -0.377, P = 0.008) in the range of 0-26 year old, whereas no significant relationship was found between age and PBMNCs' RNA content of healthy controls in the same range of ages.Conclusion: RNA content of PBMNCs from DS patients decreases rapidly with age. This is the first work on the age-dependent decrease of the RNA content in PBMNCs of DS patients. q 2005 International Society for Analytical Cytology

Nuclear protein contents in peripheral blood mononuclear cells of trisomy 21 infants

“…Present report shows that average nuclear protein content of PBMC measured by flow cytometry (FC) from DS infants is statistically higher than that of controls. The average nuclear protein levels of PBMC from DS patients decrease, however, with the age of the patients similar as seen in the case of RNA levels (24,25) in PBMC of these patients.…”

“…This in vivo (24) and in vitro RNA levels (25) decline, however, with the ages of the patients, to become finally lesser than that of controls as early as in the age of 15-20s.…”

Age‐dependent decreases in mitogen‐stimulation level and RNA content in peripheral blood mononuclear cells of down syndrome patients

“…Precocious aging in immune system (28), immuno impairing in general (29)(30)(31), decrease in number of peripheral T-lymphocytes with the phenotype of helper cells (CD4) (32,33) of DS individuals are consistent with our results; since our unpublished results show that PHA stimulates principally and strongly CD4 and CD8 T-lymphocytes. Although the value of RNA contents in nonstimulated (11) and stimulated PBMC as given in this study is higher in infants and children with DS, these subjects suffer nonetheless from immune deficiency. In fact, RNA excess in the cells of DS infants compared to controls appears unnecessary/useless, even proposed to be harmful because of the wasted energy in producing unnecessary RNA transcript (9).…”

“…Flow cytometric evaluation of cellular RNA content has been successfully achieved for the comparative purpose (10). We have shown in a previous study that RNA content in nonstimulated (in vivo) peripheral blood mononuclear cells (PBMC) of DS patients' decreases with the increasing age of DS patients (11). The present study shows that PBMC from DS patients undergo decreased phytohemagglutinin (PHA)-stimulation ratio with age.…”

“…It is known that cells withdrawn from the cell cycle (quiescent cells, G 0, G 1Q ) have, on average a 5-to 10-fold fewer ribosomes than their cycling counterparts (10), and it was observed by us that in vivo RNA content of PBMC from DS patients decreases rapidly with age (11). Thus, when we measure RNA in PHA-stimulated cells, our mean RNA content in PBMC depends on the percentage of stimulated cells (mitogenic stimulation index).…”