IMBALANCE OF THE CD4+ SUBPOPULATIONS EXPRESSING CD45RA AND CD29 ANTIGENS IN THE PERIPHERAL-BLOOD OF ADULTS AND CHILDREN WITH DOWN-SYNDROME

Peripheral blood lymphoid subsets expressing either CD45RA or CD29 antigens, were quantified in 30 children and 59 adults with Down Syndrome and appropriate age-matched controls, by dual immunofluorescence and flow cytometry. Down's patients, both adults and children, displayed a significant decrease of CD4+CD45RA+ cells in comparison with the observed in their age-matched controls, but no difference was found in the CD4+CD29+ subset. These results show clearly the imbalance of these subpopulations in the peripheral blood of individuals with Down syndrome that result in the inversion of the CD45RA/CD29 ratio, due to a major reduction of the CD45RA subset. No obvious difference was found in the CD45RA/CD29 ratio within the CD4 negative cells. Abnormalities of these subpopulations could be indicative of early senescence of the immune system, since age-related changes in Down's persons were in parallel with those observed in normal individuals and the proportion of both subpopulations were roughly similar in Down's children and normal adults.