title: Clonal growth and maturation to immunoglobulin secretion in vitro of every growth-inducible B lymphocyte.
abstract: The frequency of normal murine B lymphocytes initiating growth in diluted suspension cultures in the presence of a B cell mitogen, such as lipopolysaccharide, can be increased approximately 10(4) fold by the addition of 2 X 10(6) normal thymus cells per ml. This increase in the frequency of growing cells by thymus cells can also be observed with X63-AG8 myeloma tumor cells secreting IgG1. Thus thymus cells may not contribute growth-stimulating factors, but may supply growth-supporting factors. Culture medium and plastic dishes can be conditioned by preincubation with thymus cells for a day after which the thymus cells may be omitted from further culture for maximal B cell growth. Irradiation of thymus cell abolishes their growth-enhancing properties. Thymus cells can be syngeneic and allogeneic with the growing B cells. The frequency of growing LPS-reactive, normal B cells in spleen of 6-8 week old C3H/Tif mice was determined by limiting dilution analysis to be one of three splenic B cells. With this limiting dilution analysis, it was also shown that the cloning efficiency of XB3-AG8 myeloma tumor cells in suspension culture in the presence of thymus cells is practically 100%. Analysis of the growth kinetics of single clones of LPS-reactive, normal B cells shown that these B cells divide every 18 hr. Within the first 126 hr of growth, every B cell in the clone divides, and every dividing B cell in this clone secretes sufficient immonoglobulin to form a hemolytic plaque. The conditions of in vitro suspension cultures of murine B lymphocytes are therefore perfect to the extent that every B cell capable of growth will grow as a single clone.
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D002455:Cell Division; D002999:Clone Cells; D003470:Culture Media; D006462:Hemolytic Plaque Technique; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D008070:Lipopolysaccharides; D008213:Lymphocyte Activation; D013601:T-Lymphocytes
chemical_list: D003470:Culture Media; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008070:Lipopolysaccharides