Adult bone marrow contains precursors for CD5+ B cells.
To determine directly whether B cell precursors of adult origin are capable of generating CD5+ B cells, we reconstituted neonatal C3H. SCID mice with adult C57BL/6 bone marrow and analyzed splenic B cells 10 months later. Surface staining and flow cytometry revealed that the B cells were of donor origin and that 30% were CD5+. This confirms that in vivo generated CD5+ B cells can be adult derived. After anti-IgM (but not lipopolysaccharide) stimulation in vitro, virtually all of the B cells from the bone marrow-reconstituted mice expressed surface CD5. Sequence analysis of expressed VHDJH genes from the CD5+ B cells present after anti-IgM stimulation revealed a high frequency of N nucleotide addition in CDR3 regions. The presence of N nucleotides indicates that these sequences were derived from CD5+ B cells of adult origin rather than from long-lived fetal precursor B cells present in either the adult bone marrow at the time of transfer or adult spleen. These experiments demonstrate conclusively that adult bone marrow contains precursors for CD5+ B cells and that unlike fetal liver-derived precursors these express terminal deoxynucleotidyl transferase.
Department of Pathology, Tufts University School of Medicine, Boston, MA 02111, USA.
C A
CA
Huang
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C
Henry
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J
Iacomini
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T
Imanishi-Kari
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HH
Wortis
D000818:Animals; D000955:Antigens, T-Independent; D001402:B-Lymphocytes / Q000166:cytology* / Q000201:enzymology; D001853:Bone Marrow / Q000201:enzymology; D001854:Bone Marrow Cells; D018956:CD5 Antigens / Q000378:metabolism*; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism*; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005803:Genes, Immunoglobulin; D006410:Hematopoiesis; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D016513:Mice, SCID
D000955:Antigens, T-Independent; D018956:CD5 Antigens; D004253:DNA Nucleotidylexotransferase