Lau C Y, Melchers F, Miller R G, Phillips R A
J Immunol. 1979 Apr;122(4):1273-7.
Adult bone marrow contains both B lymphocytes and their immediate precursors, pre-B cells. These two cells differ in size and can be separated by velocity sedimentation; B cells are enriched in the subpopulation of cells sedimenting at between 2.0 and 3.5 mm/hr and pre-B cells in the subpopulation between 5.0 and 7.0 mm/hr. Incubation of pre-B cells in vitro for 4 or 5 days leads to their differentiation into functional B lymphocytes. The transition form pre-B to B appears to occur in two steps. The first step gives mitogen responsive B cells with an intermediate sedimentation velocity and the second step produces typical small, slowly sedimenting B cells. Pre-B cells can be quantified by using a limiting dilution assay and occur at a frequency of 1/60 in the subpopulation of rapidly sedimenting bone marrow cells.
成人骨髓中含有B淋巴细胞及其直接前体细胞，即前B细胞。这两种细胞大小不同，可通过速率沉降法分离；B细胞富集于沉降速度在2.0至3.5毫米/小时之间的细胞亚群中，前B细胞则在5.0至7.0毫米/小时之间的亚群中。前B细胞在体外培养4或5天会分化为功能性B淋巴细胞。从前B细胞到B细胞的转变似乎分两步进行。第一步产生对有丝分裂原反应性的、沉降速度中等的B细胞，第二步产生典型的、体积小、沉降缓慢的B细胞。前B细胞可用有限稀释法进行定量，在快速沉降的骨髓细胞亚群中的出现频率为1/60。
