Resistance of activated human Th2 cells to NO-induced apoptosis is mediated by gamma-glutamyltranspeptidase.
Activation-induced death of inflammatory cells (AICD) has an important function in immune maintenance. Type 1 Th cells are known to be more susceptible to AICD than Th2 cells. In the current study we examined whether NO-induced apoptosis also preferentially eliminates Th1 cells over Th2 cells. Naive human Th lymphocytes (CD4(+)CD45RO(-)) were activated in vitro for 1 week in the presence of IL-12 plus anti-IL-4 or IL-4 plus anti-IL-12 to generate Th1- and Th2-polarized cultures respectively. Cultures were exposed to the NO donors Spermine-nonoate (Sper) and DPTA-nonoate to study NO-induced apoptosis. We found that NO preferentially induced apoptosis in Th1-polarized cells as demonstrated by Annexin staining in the presence of 10 microM Sper (70 +/- 16 versus 23 +/- 4.4% in Th2 cells P: < 0.01) and by DioC6 staining (38 +/- 10 versus 11 +/- 5% in Th2 cells, P: < 0.01). The mechanism of NO-induced apoptosis in Th1/Th2-polarized cells was distinct from AICD and Fas-induced apoptosis. Differential sensitivity between Th1- and Th2-polarized cultures originated at the level of intracellular glutathione (GSH) metabolism. GSH levels were higher in Th2 cells (1.6 +/- 0.2-fold Th1, P: < 0.01). High intracellular GSH in Th2-polarized cells did not account for reduced susceptibility to NO per se, since the inhibition of gamma-glutamyltrans-peptidase (gamma-GT), which is involved in GSH import, sensitized Th2 cells to NO-induced apoptosis without GSH depletion. Therefore, higher activity of gamma-GT in Th2 cells (2.1 +/- 0.4-fold Th1, P: < 0.001) specifically protects Th2 cells against NO-induced apoptosis. Preferential NO-induced elimination of human Th1 cells at sites of inflammation may thus select Th2 cells and contribute to immune deviation.
Division of Allergology, Faculty of Medicine, Groningen University, Groningen University Hospital, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
R
R
Roozendaal
E
E
Vellenga
M A
MA
de Jong
K F
KF
Traanberg
D S
DS
Postma
J G
JG
de Monchy
H F
HF
Kauffman
D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D005978:Glutathione / Q000032:analysis / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009589:Nitrogen Oxides; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology*; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000502:physiology*
D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide; D005723:gamma-Glutamyltransferase; D005978:Glutathione