RT Journal Article SR Electronic T1 N,N′-Diacetyl-l-cystine—the Disulfide Dimer of N-acetylcysteine—Is a Potent Modulator of Contact Sensitivity/Delayed Type Hypersensitivity Reactions in Rodents JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 1174 OP 1184 VO 288 IS 3 A1 Särnstrand, Bengt A1 Jansson, Anne-Helene A1 Matuseviciene, Giedre A1 Scheynius, Annika A1 Pierrou, Stefan A1 Bergstrand, Håkan YR 1999 UL http://jpet.aspetjournals.org/content/288/3/1174.abstract AB Oral N-acetyl-l-cysteine (NAC) is used clinically for treatment of chronic obstructive pulmonary disease. NAC is easily oxidized to its disulfide. We show here that N,N′-diacetyl-l-cystine (DiNAC) is a potent modulator of contact sensitivity (CS)/delayed type hypersensitivity (DTH) reactions in rodents. Oral treatment of BALB/c mice with 0.003 to 30 μmol/kg DiNAC leads toenhancement of a CS reaction to oxazolone; DiNAC is 100 to 1000 times more potent than NAC in this respect, indicating that it does not act as a prodrug of NAC. Structure-activity studies suggest that a stereochemically-defined disulfide element is needed for activity. The DiNAC-induced enhancement of the CS reaction is counteracted by simultaneous NAC-treatment; in contrast, the CS reaction is even more enhanced in animals treated with DiNAC together with the glutathione-depleting agent buthionine sulfoximine. These data suggest that DiNAC acts via redox processes. Immunohistochemically, ear specimens from oxazolone-sensitized and -challenged BALB/c mice treated with DiNAC display increased numbers of CD8+ cells. DiNAC treatmentaugments the CS reaction also when fluorescein isothiocyanate is used as a sensitizer in BALB/c mice; this is a purported TH2 type of response. However, when dinitrofluorobenzene is used as a sensitizer, inducing a purported TH1 type of response, DiNAC treatment reduces the reaction. Treatment with DiNAC also reduces a DTH footpad-swelling reaction to methylated BSA. Collectively, these data indicate that DiNAC in vivo acts as a potent and effective immunomodulator that can either enhance or reduce the CS or DTH response depending on the experimental conditions. The American Society for Pharmacology and Experimental Therapeutics