| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 3355412 | Immunology Letters | 2014 | 7 Pages |
•Inhibitory receptors CD307d and CD22 are not differently expressed in the aged subjects and are not related with the proliferation ability of total and DN (IgDCD27−) B cells observed in the elderly.•The IgD−CD27− (DN) B cells from elderly donors proliferate and activate telomerase when stimulated with innate and adaptive ligands.•Relative telomerase activity assay (RTA) could be a tool to monitor the aging process.
Immunosenescence is characterized by the impairment of humoral immunity with changes in the memory/naive B cell compartment. In particular we have previously reported the percentage increase of a Memory IgD−CD27− (Double Negative, DN) B cell population in aged people. In this study, we have further characterized DN B cells with the aim to better understand their contribution to immunosenescence. As DN B cells show a poor ability to proliferate in vitro, we have evaluated the expression of the inhibitory receptors CD307d and CD22 on these cells from young and old individuals. In addition we have evaluated the ability to activate DN B cells by the simultaneous use of innate (CpG) and adaptive (α-Ig/CD40) ligands. Our data demonstrate that the refractoriness to proliferate of DN B cells does not depend on the expression of inhibitory receptors, but it is due to the kind of stimulation. Indeed, when DN B cells are stimulated engaging both BCR and TLR9, they become able to proliferate and reactivate the telomerase enzyme. In the present study, we have also compared the telomerase activity in a group of people genetically advantaged for longevity as centenarian offspring (CO) and in a group of moderate–severe Alzheimer's disease (AD) patients, who represent a model of unsuccessful aging. Our study suggests that telomerase reactivation of DN B cells, as well as their number and ability in activating, depend essentially by the biological age of the subjects studied, so the evaluation of DN B cells might allow to gain insight to healthy and unsuccessful aging.
