It has been demonstrated that asymptomatic persons infected with the human immunodeficiency virus (HIV) have significantly reduced levels of extracellular glutathione.1 Serum glutathione was only one-third of the level of healthy controls. The level of glutathione (GSH) in lung epithelial lining fluid was only 60% of that in controls. All subjects were non-smokers.

http://orthomolecular.org/library/jom/1992/articles/1992-v07n02-p104.html