Takeda A, Palfree R G, Forsdyke D R
Biochim Biophys Acta. 1982 Jan 15;710(1):87-98. doi: 10.1016/0005-2760(82)90194-1.
Serum was heated at various temperatures to inactivate components which might be involved in the regulation of lysophosphatidylcholine (lysoPC) levels in rabbit lymph-node cell cultures. Cells cultured in medium containing serum preheated for 20 min at 66 degrees C ("66 degrees C-serum") were inhibited much more by exogenous lysoPC (5 microM) than were cells cultured in medium containing control serum ("38 degrees C-serum"). This was observed over a 20 h culture period as a slow increase in inhibition of cell labelling with [3H] uridine, which reflected cytotoxic cell damage. Heating serum at 66 degrees C caused (i) conversion of monomeric albumin to highly polymeric forms which were deficient in lysoPC-binding activity, (ii) transfer of lysoPC from albumin to lipoproteins, predominantly high density lipoproteins, and (iii) inhibition of two lysoPC metabolizing activities (which were detected only at low levels in control serum). Addition of albumin to cultures containing 66 degrees C-serum decreased the toxicity of lysoPC to the same extent as did the addition of control serum with an equivalent albumin content. Thus, albumin was the major heat-labile factor protecting cells against lysoPC. However, cell inhibition by lysoPC was dependent on the sequence of heating serum and lysoPC addition. Inhibition was small when lysoPC was added before heating the serum. This could not be explained by a detectable difference in the binding of lysoPC to serum components. Furthermore, although radioactive labelling of cells with [14C] lysoPC was increased in 66 degrees C-serum, this did not correlate with cell inhibition. Increased labelling with [14C] lysoPC occurred several hours before significant cell inhibition was evident and was not affected by the sequence of heating and lysoPC addition. Since preincubation of lysoPC with 66 degrees C-serum increased the inhibition, it is suggested that the heated serum lysoPC generates another factor which is responsible for the cytotoxic effects observed.
将血清在不同温度下加热，以灭活可能参与调节兔淋巴结细胞培养物中溶血磷脂酰胆碱（lysoPC）水平的成分。在含有于66℃预热20分钟的血清（“66℃血清”）的培养基中培养的细胞，比在含有对照血清（“38℃血清”）的培养基中培养的细胞，受到外源性lysoPC（5 microM）的抑制作用更强。在20小时的培养期内观察到，用[3H]尿苷标记细胞的抑制作用缓慢增加，这反映了细胞毒性损伤。将血清加热至66℃导致：（i）单体白蛋白转化为高度聚合形式，其缺乏lysoPC结合活性；（ii）lysoPC从白蛋白转移至脂蛋白，主要是高密度脂蛋白；（iii）两种lysoPC代谢活性受到抑制（在对照血清中仅以低水平检测到）。向含有66℃血清的培养物中添加白蛋白，与添加具有等效白蛋白含量的对照血清一样，在相同程度上降低了lysoPC的毒性。因此，白蛋白是保护细胞免受lysoPC影响的主要热不稳定因子。然而，lysoPC对细胞的抑制作用取决于血清加热和lysoPC添加的顺序。当在加热血清之前添加lysoPC时，抑制作用较小。这无法通过lysoPC与血清成分结合的可检测差异来解释。此外，尽管在66℃血清中用[14C]lysoPC对细胞进行放射性标记增加，但这与细胞抑制无关。在明显的细胞抑制出现数小时之前，[14C]lysoPC标记增加，并且不受加热和lysoPC添加顺序的影响。由于lysoPC与66℃血清预孵育会增加抑制作用，因此提示加热的血清lysoPC产生了另一种导致观察到的细胞毒性作用的因子。
