Regulation of cell survival during B lymphopoiesis: increased pre-B cell apoptosis in CD24-transgenic mouse bone marrow.
CD24 (heat-stable antigen) is expressed in a developmentally regulated fashion by B cell precursors in mouse bone marrow (BM), but its role in B lymphopoiesis remains obscure. A slight overexpression of CD24 in transgenic (Tg) mice leads to depletion of B lymphoid cells in BM. The present study examines whether CD24 is involved in apoptotic selection of B lineage cells under normal microenvironmental conditions in vivo. Double immunofluorescence labeling and flow cytometry have been used to quantitate the apoptotic rates of phenotypically defined B cell populations in BM of CD24-Tg mice. Apoptosis of pre-B cells expressing cytoplasmic mu heavy chains of IgM but lacking surface (s)IgM was increased both ex vivo and in short-term culture, while the number of pre-B cells was halved compared to BM of normal mice. In contrast, B220+mu- pro-B cells and sIgM+ B lymphocytes showed no significant change in either apoptosis or number. The findings provide evidence that CD24 can play a role in vivo in modulating pre-B cell apoptosis, a quality control checkpoint in B cell development.
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Department of Anatomy and Cell Biology, McGill University, Montreal, Canada.
Chappel
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MS
Humphries
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RK
Osmond
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DG
D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D017209:Apoptosis; D001402:B-Lymphocytes / Q000502:physiology*; D001854:Bone Marrow Cells / Q000502:physiology*; D051927:CD24 Antigen; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D008562:Membrane Glycoproteins; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic
D015703:Antigens, CD; D051927:CD24 Antigen; C497890:Cd24a protein, mouse; D008562:Membrane Glycoproteins