Premium
Aged mice exhibit distinct peripheral B‐cell phenotypes differing in apoptotic susceptibility: An ex vivo analysis
Author(s) -
Verdier Mireille,
Malissein Emilie,
Munteanu Eliza,
JayatVignoles Chantal,
Ratinaud MarieHélène,
Troutaud Danielle
Publication year - 2006
Publication title -
cytometry part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.316
H-Index - 90
eISSN - 1552-4930
pISSN - 1552-4922
DOI - 10.1002/cyto.a.20310
Subject(s) - propidium iodide , apoptosis , annexin , biology , microbiology and biotechnology , programmed cell death , spleen , b cell , germinal center , immunology , antibody , biochemistry
Background: Age‐related changes in the antibody response have been classically associated with alterations in T‐cell help, but increasing evidence shows that intrinsic B‐cell defects exist. This article analyzes the apoptotic susceptibility of peripheral B‐cells in aged and young control mice. Materials and Methods: Freshly isolated lymphocytes from spleen and Peyer's patches (PPs) were labeled for B‐cell lineage (B220 + cells) and germinal center B subset (GCs, B220 + /PNA + cells). Alternatively, splenic B‐cells purified by MACS were used. Apoptosis was monitored by the Annexin V binding, incorporation of 3,3 ′ ‐dihexyloxacarbocyanine iodide (DiOC 6 (3)), propidium iodide (PI) staining, and morphological changes. Moreover, intracellular Bcl‐2 expression and Bad phosphorylation status were also analyzed in B‐cells. Results: We showed in aging mice an enhanced Annexin V + /PI − cell percentage in splenic B‐lymphocytes, which was correlated with a lower ΔΨ m . By contrast, no change in apoptosis was observed in compartments known to be enriched in activated B‐cells (GCs and PPs). Analysis of Bcl‐2 levels revealed no modification. When using B‐cells purified by MACS, we strongly confirm data obtained on staining cells. Moreover, enhanced spontaneous apoptosis of splenic B‐cells in aged mice was found to be correlated with a reduced phosphorylated Bad expression. Conclusion: Increased apoptosis of resting B‐cells in old mice may be determined by an altered Bad phosphorylation, which in turn contributes to cell death by lowering the mitochondrial threshold for apoptosis. © 2006 International Society for Analytical Cytology