B lymphocyte-associated antigens on terminal deoxynucleotidyl transferase-positive cells and pre-B cells in bone marrow of the rat.
To investigate early stages of B lymphocytopoiesis in rat bone marrow (BM) before the expression of surface IgM (s mu), the populations of cytoplasmic mu-chain-positive (c mu+) pre-B cells and terminal deoxynucleotidyl transferase-positive (TdT+) cells were studied by double immunofluorescence microscopy. B lymphocytes that were s mu+ constituted 5%, c mu+s mu- pre-B cells 23%, and TdT+ cells 4% of nucleated cells in the BM of juvenile rats. TdT+ and pre-B cells ranged between 7 and 17 microns in diameter. TdT+ cells were slightly larger, with a modal diameter of 10.5 microns against 9 microns for pre-B cells. mu-Chains were absent from nearly all TdT+ cells. Their surface antigenic phenotype was studied by using a panel of mouse monoclonal antibodies (MAb) to rat B lymphocyte-associated antigens (Ig, Ia, and others) and T lymphocyte-associated antigens. Both pre-B cells and TdT+ lacked surface Ig and Ia but carried most of the other B lymphocyte-associated antigens analyzed. TdT+ and pre-B cells lacked those antigens found only on the T lineage. By using MAb HIS24 (detecting a non-Ig/Ia B lymphocyte-associated antigen) and fluorescence-activated cell sorting, TdT+ and pre-B cells were highly enriched. The results show that most TdT+ cells in rat BM are mu- but demonstrate strong similarity with pre-B cells in surface antigenic phenotype. Therefore, as suggested for man, a major proportion of rat BM TdT+ cells may be B lineage-cells before mu heavy chain gene expression.
D000818:Animals; D000954:Antigens, Surface / Q000032:analysis* / Q000145:classification; D001402:B-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D001854:Bone Marrow Cells; D002469:Cell Separation; D004253:DNA Nucleotidylexotransferase / Q000032:analysis*; D004254:DNA Nucleotidyltransferases / Q000032:analysis*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D007148:Immunoglobulin mu-Chains / Q000032:analysis; D007958:Leukocyte Count; D008297:Male; D010641:Phenotype; D051381:Rats; D011919:Rats, Inbred Strains; D011947:Receptors, Antigen, B-Cell / Q000032:analysis
D000954:Antigens, Surface; D007148:Immunoglobulin mu-Chains; D011947:Receptors, Antigen, B-Cell; D004254:DNA Nucleotidyltransferases; D004253:DNA Nucleotidylexotransferase