The aim of our research was to evaluate redox balance parameters and biomarkers 
of oxidative stress (OS) in nonstimulated and stimulated saliva as well as the 
blood of patients with plaque psoriasis compared to healthy controls. The study 
involved 40 patients with plaque psoriasis and 40 generally healthy subjects 
matched by age and gender to the study group patients. We assayed the 
concentration/activity of antioxidant enzymes: salivary peroxidase (Px), 
catalase (CAT), and superoxide dismutase (SOD) measured in unstimulated saliva 
(NWS), stimulated saliva (SWS), and erythrocytes. In plasma as well as NWS and 
SWS, we measured the concentration/activity of reduced glutathione (GSH), total 
antioxidant potential (TAC), total oxidative status (TOS), oxidative stress 
index (OSI), and markers of oxidative modification of proteins: advanced 
glycation end products (AGE), advanced oxidation protein products (AOPP), and 
lipid oxidation products: malondialdehyde (MDA) and total lipid hydroperoxide 
(LOOH). In NWS and SWS, we also evaluated the rate of reactive oxygen species 
(ROS) production. The concentration of Px, CAT, and SOD was significantly higher 
in NWS of patients with plaque psoriasis vs. healthy subjects. In SWS of 
psoriatic patients, we observed considerably higher concentration of Px and CAT, 
and in erythrocytes of patients with plaque psoriasis, the concentration of GPx 
and CAT was significantly higher compared to that in the controls. The levels of 
AOPP, AGE, MDA, and LOOH were considerably higher in NWS, SWS, and plasma of the 
study group compared to the controls. The concentration of total protein and 
salivary amylase was significantly lower in NWS and SWS of psoriatic patients 
compared to the healthy control. In the course of plaque psoriasis, we observed 
redox imbalances with prevalence of oxidation reactions. Mechanisms involved in 
the synthesis/secretion of proteins and activity of amylase were depressed in 
both glands of psoriatic patients; however, they were more inhibited in the 
parotid gland compared to the submandibular gland. TOS concentration and OSI 
value in NWS and SWS may serve as diagnostic biomarkers of plaque psoriasis.