Fischer G F, Holter W, Majdic O, Cragoe E J, Knapp W
Institute of Immunology, University of Vienna, Austria.
J Immunol. 1988 Jul 15;141(2):404-9.
The stimulation of different cell types with growth factors is often accompanied by a rapid intracellular alkalinization. By using mitogenic lectins, cluster of differentiation (CD)2 and CD3 mAb, as stimuli, we studied early changes of the intracellular pH in the activation process of resting human PBL. We found increases in free cytoplasmic Ca2+ levels and DNA synthesis but no intracellular alkalinization in the early activation phase upon stimulation with the mitogenic lectins, Con A, and PHA. Similarly stimulation with CD3 mAb led in most instances to no detectable pH shifts. Only in 7 out of 30 experiments was CD3 mAb-induced alkalinization observed. In contrast, stimulation with mitogenic combinations of anti-CD2 mAb led in all instances to rapid and clear-cut intracellular pH shifts very similar to those observed upon stimulation with PMA. In medium lacking sodium bicarbonate the intracellular alkalinization via the CD2 structure could be blocked by the amiloride analogue 5-(N-methyl-N-isobutyl)amiloride (MIA), which indicates that this increase in pH is mediated by the amiloride-sensitive Na+/H+ antiporter. Blockade of this antiporter had no negative effect, however, on T cell proliferation as measured by thymidine incorporation. In contrast, significantly enhanced proliferation rates were observed after stimulation with mitogenic combinations of anti-CD2 antibodies in the presence of MIA. No such effect of MIA could be observed in lectin induced T cell stimulation. These findings indicate that stimulation of the Na+/H+ antiporter via the CD2 structure is neither a prerequisite for T cell proliferation nor does it promote T cell growth. It rather seems to function in a regulatory role. In its absence, superinduction of proliferation can be achieved.
用生长因子刺激不同细胞类型时，细胞内往往会迅速碱化。我们以促有丝分裂凝集素、分化簇（CD）2和CD3单克隆抗体作为刺激物，研究了静息人外周血淋巴细胞（PBL）激活过程中细胞内pH值的早期变化。我们发现，在用促有丝分裂凝集素、刀豆蛋白A（Con A）和植物血凝素（PHA）刺激后的早期激活阶段，游离细胞质Ca2+水平和DNA合成增加，但细胞内没有碱化现象。同样，用CD3单克隆抗体刺激在大多数情况下也未检测到pH值变化。仅在30次实验中的7次观察到CD3单克隆抗体诱导的碱化现象。相比之下，用抗CD2单克隆抗体的促有丝分裂组合刺激在所有情况下都会导致细胞内pH值迅速且明显的变化，这与用佛波酯（PMA）刺激时观察到的情况非常相似。在缺乏碳酸氢钠的培养基中，通过CD2结构引起的细胞内碱化可被氨氯地平类似物5-（N-甲基-N-异丁基）氨氯地平（MIA）阻断，这表明这种pH值的升高是由氨氯地平敏感的Na+/H+反向转运体介导的。然而，阻断这种反向转运体对通过胸苷掺入法测量的T细胞增殖没有负面影响。相反，在用MIA存在的情况下，用抗CD2抗体的促有丝分裂组合刺激后观察到增殖率显著提高。在凝集素诱导的T细胞刺激中未观察到MIA的这种作用。这些发现表明，通过CD2结构刺激Na+/H+反向转运体既不是T细胞增殖的先决条件，也不会促进T细胞生长。它似乎起着调节作用。在其不存在的情况下，可以实现增殖的超诱导。
