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Changes in B cell antigen expressions in the elderly
No full textPO-0999 Changes in B cell antigen expression in the elderly
Ginaldi L, De Martinis M, D’Ostilio A, Marini L, Loreto MF, Profeta VF,*
Quaglino D
Department of Internal Medicine and Public Health, University of
L’Aquila, *Ser. T ASL Teramo, Italy
The involvement of the B cell compartment during senescence plays an
important role in the development of the immune dysfunction (e.g. hypergammaglobulinemia,
autoantibody production and impaired responses to
immunisations). In order to identify specific antigen expression changes on
B lymphocytes which may contribute to the immune deficiency in the elderly,
we investigated, by triple staining flow cytometry, the level of expression
of some constitutive surface markers (HLA-DR, CD19, CD20) and of a
series of adhesion molecules (CD49b, CD49d, CD50, CD62L) on B lymphocytes
from 23 healthy elderly individuals (82-100 years old, mean age
92) compared to 13 healthy young donors (20-50 years old, mean age
31). All aged donors fullfilled the admission criteria for gerontological studies
proposed by the Senicor Protocol. Both percentage and absolute number
of B lymphocytes (CD19+ and CD20+ cells) were significantly
decreased in the elderly compared to young donors. The absolute number
of B cells expressing the adhesion molecules CD49b and CD49d was lower
in elderly individuals, as well as the percentage value of B cells expressing
the adhesion molecules CD50 and CD62L. The percentage and
absolute number of B cells coexpressing the CD5 antigen was decreased
in elderly subjects. The CD20 expression antigen was increased on B lymphocytes
coexpressing the CD49b and CD49d in elderly donors compared
to young subjects. Also the CD5 density on B cells from old donors was
slightly increased compared to controls. No differences were detected in
the expression of CD19, CD50, CD49b, CD49d, CD62L and HLA-DR molecules
on B lymphocytes. Quantitative flow cytometry may be of value in
the elderly both for clinical and biological studies. The study of antigen density
changes on B cells in the elderly may allow a better understanding of
the humoral immune defects observed in these subjects and provide
insights into the functional defects of the B cell compartment characterising
immunosenescence
Studio citochimico e fenotipico dei linfociti circolanti in soggetti tossicodipendenti con infezione da HIV
No full text
CD50 and CD62L adhesion receptor expression on naive (CD45RA+) and memory (CD45RO+) T lymphocytes in the elderly
No full textA complex reshaping characterizes cellular immunity in the elderly. In particular, the hallmark of the "senescence" of the T cell compartment is a decrease in the proportion of CD45RA+ naive T lymphocytes concomitantly with an expansion of CD45RO+ memory T cells. However, in addition to age-dependent changes in their representation, phenotypical and functional anomalies also characterize naive and memory T cell populations in the elderly. Since cell adhesion molecules (CAMs) are multifunctional receptors which play important roles not only in cell-to-cell and cell-to-matrix interactions but also in signal transduction and cell activation, we analysed, by means of a three-colour flow cytometry method, the proportion, absolute number and density expression or mean fluorescence intensity (MFI) of CD50 (ICAM-3) and CD62L (L-selectin homing receptor) adhesion receptors on CD45RA+ and CD45RO+ peripheral blood CD3+ T cell subsets from 10 healthy elderly subjects and 10 young controls. Our aim was to investigate age-dependent changes in the expression pattern of these CAMs on naive and memory lymphocytes which might contribute to the remodelling of the immune system in the elderly. We considered the mean values +/- standard deviations of the percentage, absolute number and MFI of positive cells. The percentage of naive T cells expressing CD50 was not significantly modified in aged (94.8 +/- 5.0%) compared to young individuals (97.8 +/- 3.2%). On the contrary, the percentage of memory T cells exhibiting CD50 was lower in elderly than young donors (92.0 +/- 6.4 vs. 98.3 +/- 2.2%; p < 0.01). The percentage of naive T cells expressing CD62L was decreased in the elderly donors (53.3 +/- 18.8 vs. 80.8 +/- 11.0%; p < 0.001), whereas the proportion of CD62L+ memory T lymphocytes was substantially comparable between the two age groups (63.5 +/- 15.7 vs. 54.7 +/- 12.3%). The absolute number per mm(3) of CD50+ naive T cells from aged individuals was decreased (251.9 +/- 141.9 vs. 621.8 +/- 238.0/mm(3); p < 0.001), whereas memory peripheral blood T lymphocytes expressing CD50 were substantially unchanged (863.8 +/- 260.9 vs. 802.7 +/- 139.6/mm(3)). On the contrary, the absolute numbers per mm(3) of naive and memory peripheral blood T lymphocytes exhibiting CD62L were respectively decreased (190.8 +/- 133.4/mm(3)) and increased (515.1 +/- 146.8/mm(3)) in elderly donors compared to young controls (601.3 +/- 129.1 and 351.8 +/- 195.0/mm(3); p < 0.001 and p < 0.05, respectively). Finally, CD50 MFI values of naive as well as memory T cell subpopulations from aged subjects were increased compared to young donors (14.0 +/- 2.0 vs. 9.8 +/- 1.2 and 14.0 +/- 2.0 vs. 11.6 +/- 1.3; p < 0.001 and p < 0.01, respectively). CD62L was also overexpressed in both naive (8.4 +/- 1.6 vs. 6.7 +/- 1.4; p < 0.05) and memory (10.3 +/- 2.5 vs. 5.4 +/- 1.1; p < 0.001) T subsets in the elderly. CD50 and CD62L upregulation could be interpreted as a compensatory mechanism for a decreased responsiveness and a greater requirement for activation signals rather than an age-related anomaly
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