Lichtman A H, Segel G B, Lichtman M A
Blood. 1983 Mar;61(3):413-22.
A small quantity of extracellular calcium is required for the stimulation of lymphocytes by mitogens such as plant lectins. Lectin binding to the lymphocyte surface and early postbinding events that eventually lead to DNA synthesis are calcium dependent. Mitogenic lectins such as PHA and Con-A rapidly increase the size of an exchangeable pool of cell calcium and cause a smaller rise in intracellular ionized calcium. The increase in ionized calcium is so small (100-200 nM), however, that no increase in total cell calcium is measurable. When lymphocytes are stimulated by a lectin, the rate of calcium entry into the cell increases, but the plasma membrane calcium extrusion pump can prevent the total cell calcium from increasing measurably. The calcium ionophore A23187 is a lymphocyte mitogen and causes an increase in the exchangeable, ionized, and total cell calcium. The former two effects may be causal in mitogenesis; the latter effect is cytotoxic. With A23187 treatment, the rate of calcium influx exceeds the maximum rate of the plasma membrane extrusion pump and cell calcium increases in proportion to the concentration of A23187. The mitochondria, by virtue of their high membrane potential, provide a sink for the buffering of cytoplasmic calcium after A23187 treatment. Thus, the plasma membrane or mitochondria regulate the distribution of lymphocyte calcium when the cell is stimulated by mitogenic lectins or ionophores. The evidence strongly suggests that an alteration in calcium pools or an increase in cytoplasmic ionized calcium plays a role in the initiation of the biochemical reactions that lead to mitogen-induced lymphocyte proliferation in vitro and, perhaps, to the immune response.
少量细胞外钙是植物凝集素等丝裂原刺激淋巴细胞所必需的。凝集素与淋巴细胞表面的结合以及最终导致DNA合成的结合后早期事件均依赖于钙。PHA和Con - A等促有丝分裂凝集素会迅速增加细胞钙的可交换池大小，并使细胞内游离钙有较小幅度的升高。然而，游离钙的升高幅度非常小（100 - 200 nM），以至于细胞总钙含量没有可测量的增加。当淋巴细胞受到凝集素刺激时，钙进入细胞的速率增加，但质膜钙泵可以阻止细胞总钙含量有可测量的增加。钙离子载体A23187是一种淋巴细胞丝裂原，会导致可交换钙、游离钙和细胞总钙增加。前两种效应可能是有丝分裂发生的原因；后一种效应具有细胞毒性。用A23187处理后，钙内流速率超过质膜泵出的最大速率，细胞钙含量随A23187浓度成比例增加。线粒体凭借其高膜电位，在A23187处理后为缓冲细胞质钙提供了一个汇。因此，当细胞受到促有丝分裂凝集素或离子载体刺激时，质膜或线粒体调节淋巴细胞钙的分布。有力的证据表明，钙池的改变或细胞质游离钙的增加在引发导致体外丝裂原诱导的淋巴细胞增殖以及可能引发免疫反应的生化反应中起作用。
