Identification of a germ-line pro-B cell subset that distinguishes the fetal/neonatal from the adult B cell development pathway.
Studies presented here show that the expression of CD4, MHC class II (Ia,) and B220 cleanly resolves a major and a minor subset within the earliest pro-B cell population (germ-line pro-B) in adult bone marrow (BM). The major subset expresses intermediate B220 and low CD4 levels. The minor subset, which constitutes roughly 20% of the adult germ-line pro-B, expresses very low B220 levels and does not express CD4. Ia is clearly detectable at low levels on the major germ-line pro-B subset, both in wild-type adult mice and in gene-targeted mice (RAG2-/- and microMT), in which B cell development terminates before the pre-B cell stage. A small proportion of cells in the more mature pro-B cell subsets (Hardy Fractions B and C) also express Ia at this level. In contrast, Ia levels on the minor subset are barely above (or equal to) background. Surprisingly, the major germ-line pro-B cell subset found in adults is missing in fetal and neonatal animals. All of the germ-line pro-B in these immature animals express a phenotype (very low B220, no CD4, or Ia) similar to that of the minor pro-B cell subset in adult BM. Because B cell development in fetal/neonatal animals principally results in B-1 cells, these findings demonstrate that the B-1 development pathway does not include the major germ-line pro-B subset found in adult BM and hence identify a very early difference between the B-1 and -2 development pathways.
Lu
Li-Sheng
LS
Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305-5318, USA.
Tung
James
J
Baumgarth
Nicole
N
Herman
Ometa
O
Gleimer
Michael
M
Herzenberg
Leonard A
LA
Herzenberg
Leonore A
LA
D000818:Animals; D000831:Animals, Newborn; D016175:B-Lymphocyte Subsets / Q000145:classification / Q000166:cytology* / Q000276:immunology; D001854:Bone Marrow Cells / Q000145:classification / Q000166:cytology / Q000276:immunology; D015704:CD4 Antigens / Q000096:biosynthesis; D002454:Cell Differentiation; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000166:cytology* / Q000276:immunology; D000949:Histocompatibility Antigens Class II; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic
D015704:CD4 Antigens; D000949:Histocompatibility Antigens Class II; D017493:Leukocyte Common Antigens