Hawkins E D, Markham J F, McGuinness L P, Hodgkin P D
Immunology Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria 3050, Australia.
Proc Natl Acad Sci U S A. 2009 Aug 11;106(32):13457-62. doi: 10.1073/pnas.0905629106. Epub 2009 Jul 24.
In contrast to most stimulated lymphocytes, B cells exposed to Toll-like receptor 9 ligands are nonself-adherent, allowing individual cells and families to be followed in vitro for up to 5 days. These B cells undergo phases typical of an adaptive response, dividing up to 6 times before losing the impetus for further growth and division and eventually dying by apoptosis. Using long-term microscopic imaging, accurate histories of individual lymphocyte fates were collected. Quantitative analysis of family relationships revealed that times to divide of siblings were strongly related but these correlations were progressively lost through consecutive divisions. A weaker, but significant, correlation was also found for death times among siblings. Division cessation is characterized by a loss of cell growth and the division in which this occurs is strongly inherited from the original founder cell and is related to the size this cell reaches before its first division. Thus, simple division-based dilution of factors synthesized during the first division may control the maximum division reached by stimulated cells. The stochastic distributions of times to divide, times to die, and divisions reached are also measured. Together, these results highlight the internal cellular mechanisms that control immune responses and provide a foundation for the development of new mathematical models that are correct at both single-cell and population levels.
与大多数受刺激的淋巴细胞不同，暴露于Toll样受体9配体的B细胞是非自身黏附性的，这使得单个细胞及其谱系在体外可被追踪长达5天。这些B细胞经历适应性反应的典型阶段，在失去进一步生长和分裂的动力并最终通过凋亡死亡之前可分裂多达6次。通过长期显微镜成像，收集了单个淋巴细胞命运的精确历程。对谱系关系的定量分析表明，姐妹细胞的分裂时间密切相关，但这些相关性在连续分裂过程中逐渐丧失。在姐妹细胞的死亡时间之间也发现了较弱但显著的相关性。分裂停止的特征是细胞生长的丧失，而发生这种情况的分裂强烈地从原始祖细胞继承而来，并且与该细胞在第一次分裂前达到的大小有关。因此，在第一次分裂期间合成的因子基于简单分裂的稀释可能控制受刺激细胞达到的最大分裂次数。还测量了分裂时间、死亡时间和达到的分裂次数的随机分布。这些结果共同突出了控制免疫反应的细胞内机制，并为开发在单细胞和群体水平上都正确的新数学模型奠定了基础。
