title: Ly1+ PRO-B lymphocyte clones. Phenotype, growth requirements and differentiation in vitro and in vivo.
abstract: Several clones obtained from the bone marrow of a BALB/c mouse were found to contain the heavy and light chain Ig genes in the germline configuration, to express Ly1 and to carry the B cell lineage markers B-220, Lyb8 and BP-1; these clones are Pgp-1+, LFA-1+, J11d+, Mac-1+ and Thy1-, Lyt2-, L3T4-, GM1.2- and Ia-. Three clones analyzed in detail (Lyd9, LyH7 and Lyb9) have receptors for interleukin (IL) 2 and IL3 as assessed with the 7D4 and CC11 monoclonal antibodies respectively. They grow in rIL3 but not in rIL2 or rIL1; both rIL4 and rIL5 also promote their proliferation, albeit to a much lesser extent than rIL3. None of the interleukins tested alone or in various combinations promoted the clones to differentiate in vitro along the B cell pathway. Treatment with 5-Azacytidine (5-Aza) induced cell surface Ia expression but not rearrangement or expression of Ig genes. However, 5-Aza-treated Lyd9, LyH7 and Lyb9 cells co-cultured with X-ray irradiated accessory cells and LPS gave rise to Ly1+, IgM+ B lymphocytes (range 14-51%) including mu + kappa + (78-93%), and mu + lambda + (9-25%) B lymphocytes. In vivo, the Lyd9, LyH7 and Lyb9 clones gave rise to IgM+ B lymphocytes (8.5-17%) including mu + kappa +, and mu + lambda +, but not to Lyt2+ or L3T4+ T lymphocytes after 4-6 weeks of transfer into Scid mice. Our results indicate that Ly1+ IgM+ cells comprise a subpopulation of B lymphocytes that is derived from IL3-responsive Ly1+ PRO-B lymphocytes.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis*; D000950:Antigens, Ly / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D002999:Clone Cells; D005803:Genes, Immunoglobulin; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D010641:Phenotype; D013154:Spleen / Q000166:cytology / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte; D000950:Antigens, Ly; D000954:Antigens, Surface