Tanigawa T, Kotake Y, Tanigawa M, Reinke L A
National Biomedical Center for Spin Trapping and Free Radicals, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
Free Radic Res. 1995 Apr;22(4):361-73. doi: 10.3109/10715769509145648.
Superoxide generation by polymorphonuclear leukocytes (PMNs) in suspension, or adherent to glass or plastic, after stimulation with N-formylmethionyl-leucyl-phenylalanine or phorbol myristate acetate was measured by cytochrome c reduction and spin trapping. Amounts of superoxide generated by adherent PMNs were inversely related to cell density. The generation of hydrogen peroxide was also inhibited at higher cell densities. In contrast to adherent cells, superoxide released by PMNs in suspension linearly increased with respect to cell number over a wider range. Microscopic observation indicated that the number of cells in mutual contact increased rapidly at cell densities higher than 4 x 10(4) cells/cm2, and inhibition of superoxide became apparent at higher cell densities. Mediators which could be released by PMNs, such as NO and adenosine, were not the cause of inhibition. These data suggest that mutual contact of PMNs suppresses their generation of superoxide. Survival rates of PMNs after stimulation increased at higher densities, indicating that the mutual contact-induced inhibition of superoxide generation by PMNs may be physiologically relevant at sites of inflammation.
通过细胞色素c还原和自旋捕获法，测定了悬浮状态下或粘附于玻璃或塑料上的多形核白细胞（PMN）在用N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸或佛波酯肉豆蔻酸酯刺激后产生超氧化物的情况。粘附的PMN产生的超氧化物量与细胞密度呈负相关。在较高细胞密度下，过氧化氢的产生也受到抑制。与粘附细胞不同，悬浮状态下的PMN释放的超氧化物在更宽范围内随细胞数量呈线性增加。显微镜观察表明，在细胞密度高于4×10⁴个细胞/cm²时，相互接触的细胞数量迅速增加，并且在较高细胞密度下超氧化物的抑制作用变得明显。PMN可能释放的介质，如一氧化氮和腺苷，不是抑制的原因。这些数据表明，PMN的相互接触会抑制其超氧化物的产生。刺激后PMN的存活率在较高密度下增加，表明PMN相互接触诱导的超氧化物产生抑制在炎症部位可能具有生理相关性。
