8-HYDROXYDEOXYGUANOSINE - A MARKER OF OXIDATIVE DNA-DAMAGE IN SYSTEMIC LUPUS-ERYTHEMATOSUS

8-Hydroxydeoxyguanosine (80HDG) is a specific marker of oxidative dama ge to DNA. We have observed that patients with SLE (systemic lupus ery thematosus), have undetectable levels of urinary 80HDG by HPLC. Furthe r analysis by GC-MS confirmed that levels of 80HDG in SLE urine were 1 0(3)-fold lower than in an age- and sex-matched control group. Experim ents utilising cultures of SLE and normal lymphocytes exposed to H2O2 confirmed the impaired ability of SLE lymphocytes to repair 80HDG. We subsequently observed in SLE patients that 80HDG had accumulated in lo w molecular weight DNA associated with circulating immune complexes. W e suggest that oxygen radicals may induce pathology in SLE by maintain ing the presence of an antigenic form of DNA in the circulation.