B cell precursors are decreased in senescent BALB/c mice, but retain normal mitotic activity in vivo and in vitro.
The numbers of phenotypic (sIg- Ly5[220]+) and functional B cell precursors were significantly reduced in the bone marrow of senescent (22-24 months old) BALB/c mice when compared to their young (2-4 months old) cohorts. Little alteration in the numbers of B cell precursors occurred during the first 12 months of life in this strain. In contrast, an accelerated loss of B cell precursors between 15 and 18 months of age was observed. In particular, the levels of small Ly5(220)+ B cell precursors were decreased with advanced age, although a decline in numbers of large sIg- Ly5(220)+ B cell precursors was also evident. The percentages of large sIg- Ly5(220)+ B cell precursors in (S + G2/M) stages of cell cycle were similar (e.g., 60-80%) in aged and young BALB/c mice. Importantly, Ly5(220)+ pre-B cells from both young and aged BALB/c mice, either present in vivo or derived from Ly5(220)- cells in vitro, were capable of proliferation in response to rIL-7. These observations suggest that the aging process results in a progressive decline in the numbers of pre-B cells; however, this apparently is not due to failure of B lineage precursor cells to respond to growth mediators either in vivo or in vitro.
Riley
R L
RL
Department of Microbiology and Immunology, University of Miami School of Medicine, Florida 33101.
Kruger
M G
MG
Elia
J
J
D000375:Aging / Q000276:immunology*; D000818:Animals; D000950:Antigens, Ly / Q000032:analysis; D001402:B-Lymphocytes / Q000502:physiology*; D001854:Bone Marrow Cells; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D015851:Interleukin-7 / Q000494:pharmacology; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008938:Mitosis; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D011994:Recombinant Proteins / Q000494:pharmacology
D000950:Antigens, Ly; D015851:Interleukin-7; D011947:Receptors, Antigen, B-Cell; D011994:Recombinant Proteins