Red blood cells upregulate cytoprotective proteins and the labile iron pool in dividing human T cells despite a reduction in oxidative stress
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- 作者：Fonseca ; Ana Mafalda ; Pereira ; Carlos F. ; Porto ; Graç ; a ; Arosa ; Fernando A.
- 关键词：T cells ; Red blood cells ; Oxidative stress ; Apoptosis ; Ferritin ; Transferrin receptor ; Iron ; Heme oxygenase ; Growth ; Survival ; Free radicals
- 刊名：Free Radical Biology and Medicine
- 出版年：2003
- 出版时间：December 1, 2003
- 年：2003
- 卷：35
- 期：11
- 页码：1404-1416
- 全文大小：389 K
文摘
We have recently reported that red blood cells (RBC) promote T cell growth and survival by inhibiting activation-induced T cell death. In the present study, we have examined parameters of oxidative stress and intracellular iron in activated T cells and correlated these data with the expression of ferritin, heme oxygenase-1 (HO-1), and the transferrin receptor CD71. T cells growing in the presence of RBC had reduced levels of reactive oxygen species (ROS) and oxidatively modified proteins, suggesting that RBC efficiently counteracted ROS production on the activated T cells. Flow cytometry and immunodetection demonstrated that T cells dividing in the presence of RBC had increased levels of intracellular ferritin rich in L-subunits and HO-1 along with a downmodulation in CD71 expression. Finally, using the fluorescent iron indicator calcein and flow cytometry analysis, we were able to show that a relative amount of the labile iron pool (LIP) was upregulated in T cells growing in the presence of RBC. These findings are consistent with a typical response to iron overload. However, neither heme compounds nor ferric iron reproduced the levels of expansion and survival of T cells induced by intact RBC. Altogether, these data suggest that RBC inhibit apoptosis of activated T cells by a combination of ROS scavenging and upregulation of cytoprotective proteins such as ferritin and HO-1, which may counteract a possible toxic effect of the increased intracellular free iron.