title: Monoclonal origin of B lymphocyte colony-forming cells in spleen colonies formed by multipotential hemopoietic stem cells.
abstract: Spleen colonies produced by transplanting lethally irradiated mice with either 12 day fetal liver or adult bone marrow cells were found to contain B- lymphocyte colony-forming cells (BL-CFC) . The proportion of BL-CFC positive spleen colonies did not increase substantially between 8 and 14 days after transplantation, the range being 18-45 percent. However, the absolute number of BL-CFC per spleen colony varied considerably (between 1 and 10,318), although the majority of colonies contained less than 200 BL-CFC. Irrespective of the time after transplantation, smaller spleen colonies were found to have a higher frequency of BL-CFC than larger spleen colonies. To determine the possible clonal origin of BL-CFC from spleen colony- forming unit (CFU-S), CBA mice were injected with equal numbers of CBA and CBA T(6)/T(6) fetal liver or adult bone marrow cells. Analysis of 7-15-day spleen colonies demonstrated that 90 percent were either exclusively T(6) positive or T(6) negative and approximately equal numbers ofboth colony types were observed. B-lymphocyte colonies were grown and successfully karyotyped from 19 spleen colonies. When compared with the original spleen colony karyotype the B-lymphocyte colony cells karyotype was identical in all 19 cases. In 3 of the 19 colonies analyzed a mixture of T(6) positive and T(6) negative karyotypes was present and identical proportions of the karyotypes were present in the pooled B-lymphocyte colony cells and spleen colony cells. The data indicate that the B-lymphocyte colony-forming cells detected in spleen colonies are genuine members of the hemopoietic clone derived from the initiating hemopoietic stem cell (CFU-S).
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D002999:Clone Cells / Q000276:immunology*; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D007621:Karyotyping; D008099:Liver / Q000196:embryology; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D009924:Organ Culture Techniques; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D013154:Spleen / Q000166:cytology*
chemical_list: D011947:Receptors, Antigen, B-Cell