The human fetal omentum: a site of B cell generation.
The fetal mouse omentum has been shown to be a source of precursors that exclusively reconstitutes Ly1+ B cells and the closely related Ly1- sister population, but not conventional B cells or T cells. We have extended these studies to compare B cell development in the human fetal omentum, liver, and spleen, and to demonstrate that the pro/pre-B cell compartment (CD24+, sIgM-) is detected in the omentum and liver but not spleen as early as 8 wk of gestation. From 8 to 12 wk of gestation, the proportions of IgM+ cells that were pre-B cells (cIgM+/sIgM-) in the omentum and liver were 53 +/- 15% and 45 +/- 13%, respectively, and IgM+ cells were not detectable in the spleen. After 12 wk, the percentage of pre-B cells was unchanged in the fetal liver (41 +/- 10%) but decreased significantly in the omentum (25 +/- 14%); pre-B cells were now detected in the spleen but at much lower percentages (2 +/- 3%) than either the omentum or liver. The nuclear enzyme, Tdt, was detected in approximately 25% of the CD24+ cells in the omentum and liver during the 8-12-wk time period, however, Tdt+ cells were not detected in the spleen. Approximately 40% of the mature B cells found in the omentum and spleen were CD5+ compared with only 20% in the liver. These results demonstrate that the fetal omentum, like the fetal liver and bone marrow, is a primary site of B cell development.
Solvason
N
N
Department of Microbiology, University of Alabama, Birmingham 35294.
Kearney
J F
JF
D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D051927:CD24 Antigen; D018956:CD5 Antigens; D004253:DNA Nucleotidylexotransferase / Q000276:immunology; D005333:Fetus; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005865:Gestational Age; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D007958:Leukocyte Count; D008099:Liver / Q000166:cytology / Q000196:embryology; D008562:Membrane Glycoproteins; D009852:Omentum / Q000196:embryology*; D013154:Spleen / Q000166:cytology / Q000196:embryology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D051927:CD24 Antigen; C497889:CD24 protein, human; D018956:CD5 Antigens; D007075:Immunoglobulin M; D008562:Membrane Glycoproteins; D004253:DNA Nucleotidylexotransferase