TY - JOUR
T1 - Inhibition of human T lymphoblast proliferation by hydroquinone
AU - Li, Qing
AU - Geiselhart, Lisa
AU - Mittler, James N.
AU - Mudzinski, Stanley P.
AU - Lawrence, David A.
AU - Freed, Brian M.
N1 - Funding Information:
1This work was supported by United States Public Health Service NIH Grant ES-05673 from the National Institute of Environmental Health Sciences, National Institute of Health.
PY - 1996/8
Y1 - 1996/8
N2 - Hydroquinone (HQ) is a major metabolite of benzene and is present in large quantities in cigarette tar as a result of the combustion of tobacco leaf pigments. We hypothesize that the immunosuppressive effects of cigarette smoking are due, in part, to the deposition of large quantities of HQ in the lungs. Exposure of primary human T lymphoblasts (HTL) in vitro to 50 μM HQ blocked IL-2-dependent proliferation by >90% with no loss in viability. Inhibition of DNA synthesis was observed immediately after the addition of HQ to the cells. However, this effect could be reversed up to 6 hr later by simply washing the cells and reculturing them in the absence of HQ. HQ did not significantly alter intracellular glutathione levels up to 24 hr later, and the presence of 50 μM 2-mercaptoethanol or 500 μM dithiothreitol during the treatment did not prevent inhibition of DNA synthesis. HQ did not block binding of 125I-IL-2 to the cells, but inhibited the IL-2-dependent progression of HTL through S phase of the cell cycle. These observations demonstrate that HQ, in concentrations comparable to those found in cigarette tar, is a potent inhibitor of IL-2-dependent T cell proliferation and may therefore help to explain the potent immunosuppressive effects of cigarette smoke on lung T lymphocytes.
AB - Hydroquinone (HQ) is a major metabolite of benzene and is present in large quantities in cigarette tar as a result of the combustion of tobacco leaf pigments. We hypothesize that the immunosuppressive effects of cigarette smoking are due, in part, to the deposition of large quantities of HQ in the lungs. Exposure of primary human T lymphoblasts (HTL) in vitro to 50 μM HQ blocked IL-2-dependent proliferation by >90% with no loss in viability. Inhibition of DNA synthesis was observed immediately after the addition of HQ to the cells. However, this effect could be reversed up to 6 hr later by simply washing the cells and reculturing them in the absence of HQ. HQ did not significantly alter intracellular glutathione levels up to 24 hr later, and the presence of 50 μM 2-mercaptoethanol or 500 μM dithiothreitol during the treatment did not prevent inhibition of DNA synthesis. HQ did not block binding of 125I-IL-2 to the cells, but inhibited the IL-2-dependent progression of HTL through S phase of the cell cycle. These observations demonstrate that HQ, in concentrations comparable to those found in cigarette tar, is a potent inhibitor of IL-2-dependent T cell proliferation and may therefore help to explain the potent immunosuppressive effects of cigarette smoke on lung T lymphocytes.
UR - http://www.scopus.com/inward/record.url?scp=0030220525&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030220525&partnerID=8YFLogxK
U2 - 10.1006/taap.1996.0171
DO - 10.1006/taap.1996.0171
M3 - Article
C2 - 8806848
AN - SCOPUS:0030220525
SN - 0041-008X
VL - 139
SP - 317
EP - 323
JO - Toxicology and Applied Pharmacology
JF - Toxicology and Applied Pharmacology
IS - 2
ER -