title: Immunoglobulin heavy chain gene diversification in the long-term bone marrow culture of normal mice and mice with severe combined immunodeficiency.
abstract: The change of immunoglobulin heavy (H) chain gene configuration during the differentiation of B cells from their early precursors was investigated in long-term cultures of bone marrow cells (LTBC). Hemopoietic stem cells are maintained in LTBC described by Dexter et al. (J. Cell. Physiol. 1977. 91: 335; LTBC-D), which supports the differentiation of myeloid lineage cells but not B lineage cells. By simply shifting the culture condition to that devised by Whitlock and Witte (Proc. Natl. Acad. Sci. USA 1982. 79: 3608; LTBC-B) to support the development of B lineage cells, surface IgM-bearing (sIgM+) B cells became detectable by the 2nd week after the shift and the number quickly increased thereafter, while the number of polymorphonuclear cells and granulocyte-macrophage colony-forming cell (CFU-c) decreased rapidly. H chain gene configuration of the developing cells in the culture was examined by Southern blot analysis of Eco RI-digested DNA with a JH probe. Whereas rearranged JH gene configuration was not detectable in the DNA from LTBC-D cells, it first appeared 2 weeks after the shift, and the level of the rearrangement rapidly increased thereafter as the intensity of JH band of germ-line configuration decreased. Almost all the cells in the culture had undergone H chain gene rearrangement in both chromosomes by the 6th week after the shift. During 2 to 4 weeks after the shift, a cluster of bands spanning around 4.5-5.5 kb appeared dominant among the rearranged configurations of JH gene and then it decreased in intensity as the pattern of JH band became a more homogeneous smear. The distribution of rearranged JH bands observed during 3-4 weeks after the shift was strikingly similar to that observed in normal spleen B cells. By semi-quantitative analysis of the intensity of JH and DSP2 bands remaining in germ-line configuration, it was found that the loss of germ-line JH band was far more rapid than that of germ-line DSP2 bands in the developing B cells in vitro. This result is consistent with the conclusion obtained in B cell tumor lines that D to J assembly occurred first and was followed by V to DJ assembly in this culture system. Taken together, it is likely that the process of H chain gene diversification in this culture system may represent the actual process during B cell differentiation in vivo. Differentiative capacity of bone marrow stem cells from mouse with severe combined immunodeficiency (SCID) was also analyzed in the same culture system.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D003101:Collodion; D003114:Colony-Forming Units Assay; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005815:Genetic Code; D006412:Hematopoietic Stem Cells / Q000166:cytology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007075:Immunoglobulin M / Q000378:metabolism; D007153:Immunologic Deficiency Syndromes / Q000276:immunology*; D051379:Mice; D008815:Mice, Inbred Strains / Q000276:immunology*; D013997:Time Factors
chemical_list: D000954:Antigens, Surface; D003470:Culture Media; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D003101:Collodion