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Exp Gerontol. 2003 Oct;38(10):1137-47.

Aged mice exhibit distinct B cell precursor phenotypes differing in activation, proliferation and apoptosis.

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Department of Microbiology and Immunology, University of Miami School of Medicine, P.O. Box 016960 R138, Miami, FL 33101, USA.


Senescence in murine models is associated with a reduction, albeit heterogeneous, in bone marrow pre-B cells. We have categorized aged BALB/c mice into two phenotypes based on their patterns of pre-B/pro-B cell loss. Each phenotype is characterized by distinct responses to the growth cytokine IL-7 and capacity for survival in vitro. A 'moderate' loss of late-stage pre-B cells (25-80%) coincided with decline in proliferation to rmIL-7. This was also associated with a decrease in the frequency of pro-B cells which increased phosphotyrosine content upon IL-7 stimulation, an indicator of early activation events. A 'severe' loss of pre-B cells (>80%) resulted in a reduced pro-B cell pool which retained normal activation and proliferative responses to IL-7. B cell precursors from aged mice with severe alterations in B lymphopoiesis displayed increased susceptibility to apoptosis in comparison to both aged mice with moderate B cell precursor loss and young mice. Conceivably, during senescence, aged mice may initially accumulate B cell precursors which are poorly responsive to IL-7. Progressively, these refractory B cell precursors may be eliminated via apoptosis; however, the remaining limited pool of B cell precursors retains the capacity to respond to IL-7 stimulation.

[Indexed for MEDLINE]

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