Ageing mechanisms of hemopoietic system in senescence accelerated (SAM-P) mice.

衰老加速（SAM-p）小鼠显示出外周血细胞数量随年龄的显著减少。该品系小鼠的青年和老年之间的相互骨髓移植表明，老年小鼠脾脏的分化支持功能不如青年小鼠活跃。我们测定了幼年和老年SAM-P小鼠粒细胞-巨噬细胞集落刺激因子（GM-CSF）的产生，老年小鼠产生的GM-CSF明显低于幼年小鼠。对IL-E刺激的反应程度（已知IL-E刺激诱导鼠骨髓细胞产生GM-CSF）在年轻小鼠和老年小鼠之间没有差异，尽管在这种情况下老年小鼠中的GM-CSF总量比年轻小鼠中的少，年轻和年老的小鼠白细胞介素-6的产生水平没有差异。这些结果表明，细胞因子产生的相关减少是老年SAM-P小鼠外周血细胞产生减少的原因。

Senescence accelerated (SAM-p) mice show a significant decrease in the number of peripheral blood cells with age. Mutual bone marrow transplantation between young and old mice of this strain revealed that the differentiation-supporting function of the spleen of the old mice was less active than that in the young mice.To elucidate the possible decrease in cytokine production by the hemopoietic microenvironmet of the old mice, we have assayd the production of granulocyte-macrophage colony stimulating factor (GM-CSF) in the young and old SAM-P mice.Old mice produced much less GM-CSF compared to young mice. Degree of the response to IL-E stimulation, which is known to induce GM-CSF production by the murine bone marrow cells, was not different between young and old mice, although the total amount of GM-CSF was less in the old mice than that in the young mice in this case, as well.There was no difference in the level of interleukin-6 production between young and old mice.These results suggest that age-related decrease in cytokine production is responsible for the decreased production of peripheral blood cells in the old SAM-P mice.