Xiong Q B, O'Hara M D, Pollard M D, Leeper D B
Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Int J Hyperthermia. 1996 Jan-Feb;12(1):77-86. doi: 10.3109/02656739609023691.
We have previously reported that murine granulocyte-macrophage progenitors (CFU-GM) are capable of developing thermotolerance during chronic hyperthermia at temperatures of 40 to 42 degrees C. However, a differential profile of intrinsic thermal response and, in particular, the capability of developing thermotolerance during chronic heating was identified between CFU-GM and macrophage colony-forming units (CFU-M) stimulated respectively, by lung conditioned medium (LCM) and L929 cell conditioned medium (CCM). Nucleated marrow cells treated in vitro were cultured in McCoy's 5A medium plus 15% fetal bovine serum (FBS) in semisolid agar with 10% of CCM. Two different treatment protocols were used in this study to determine the kinetics of thermotolerance in CFU-M: (1) nucleated marrow from mouse tibia and femur were chronically heated in vitro at temperatures of 40, 41 and 42 degrees C (up to 480 min) or (2) nucleated marrow cells were heated over a period of 90 min stepwise from 37 to 42 degrees C, at a heating rate of 0.056 degrees C/min, before exposure to 42 degrees C. The amount of thermotolerance developed was analysed at various times after chronic incubation at 40-42 degrees C by a challenge with 15 min at 44 degrees C. In contrast to CFU-GM, the surviving fraction of CFU-M heated with 15 min at 44 degrees C did not increase during chronic hyperthermia at 40 degrees C for up to 480 min indicating failure to develop thermotolerance. However, CFU-M were able to develop thermotolerance during prolonged incubation at 41 and 42 degrees C, although to a much less extent than observed in CFU-GM. In other words, there was much less development of thermotolerance in murine CFU-M compared to that in CFU-GM. Furthermore, a slow temperature transit from 37 to 42 degrees C over 90 min before exposure to 42 degrees C induced CFU-M to develop thermotolerance. The thermotolerance ratio (TTR, the ratio of the surviving fraction at maximum tolerance versus normotolerance) increased from a maximum of 3.5 after 180 min at 42 degrees C (no warm-up) to a maximum of 4.1 after 60 min at 42 degrees C when the cells received a slow warm-up to 42 degrees C. This implies that in the murine bone marrow granulocyte/macrophage lineage, CFU-M does not normally develop thermotolerance during hyperthermia and that the colony forming unit-granulocyte (CFU-G) and CFU-GM play a more critical role than CFU-M in the initiation and promotion of thermotolerance during chronic hyperthermia. However, in a situation that simulates the slow heat-up used clinically in wholebody hyperthermia, e.g., the 90 min slow warm-up from 37 to 42 degrees C, stimulated CFU-M to develop greater thermotolerance more rapidly than during rapid heating.
我们之前曾报道，小鼠粒细胞-巨噬细胞祖细胞（CFU-GM）在40至42摄氏度的慢性高温期间能够产生热耐受性。然而，分别用肺条件培养基（LCM）和L929细胞条件培养基（CCM）刺激的CFU-GM和巨噬细胞集落形成单位（CFU-M）之间，内在热反应的差异特征，尤其是在慢性加热期间产生热耐受性的能力被确定。体外处理的有核骨髓细胞在含有10%CCM的半固体琼脂中的 McCoy's 5A培养基加15%胎牛血清（FBS）中培养。本研究采用两种不同的处理方案来确定CFU-M中热耐受性的动力学：（1）从小鼠胫骨和股骨采集的有核骨髓在体外于40、41和42摄氏度（长达480分钟）进行慢性加热，或（2）有核骨髓细胞在暴露于42摄氏度之前，以0.056摄氏度/分钟的加热速率从37摄氏度逐步加热90分钟至42摄氏度。在40至42摄氏度慢性孵育后的不同时间，通过在44摄氏度进行15分钟的激发来分析产生的热耐受性量。与CFU-GM相反，在40摄氏度长达480分钟的慢性高温期间，在44摄氏度加热15分钟的CFU-M的存活分数没有增加，表明未能产生热耐受性。然而，CFU-M在41和42摄氏度长时间孵育期间能够产生热耐受性，尽管程度比在CFU-GM中观察到的要小得多。换句话说，与CFU-GM相比，小鼠CFU-M中热耐受性的产生要少得多。此外，在暴露于42摄氏度之前，在90分钟内从37摄氏度缓慢升温至42摄氏度诱导CFU-M产生热耐受性。热耐受性比率（TTR，最大耐受性时的存活分数与正常耐受性时的存活分数之比）从在42摄氏度（无预热）180分钟后最高的3.5增加到当细胞接受缓慢升温至42摄氏度时在42摄氏度60分钟后最高的4.1。这意味着在小鼠骨髓粒细胞/巨噬细胞谱系中，CFU-M在高温期间通常不会产生热耐受性，并且在慢性高温期间热耐受性的起始和促进过程中，集落形成单位-粒细胞（CFU-G）和CFU-GM比CFU-M发挥更关键的作用。然而，在模拟临床上全身热疗中使用的缓慢升温的情况下，例如从37摄氏度到42摄氏度的90分钟缓慢升温，刺激CFU-M比快速加热期间更快地产生更大的热耐受性。
