The relationship between plasma levels of two platelet activation markers, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4), and the severity of atopic dermatitis (AD) and psoriasis was studied in 44 AD patients, 16 psoriasis patients and 22 controls. Plasma beta-TG and PF4 levels were significantly higher (p < 0.05) in patients with AD or psoriasis compared to healthy controls; beta-TG and PF4 levels decreased after treatments. Both chemokines also correlated with the SCORing Atopic Dermatitis (SCORAD) index, while PF4 also correlated with the Psoriasis Area and Severity Index (PASI) score. No significant differences were found in beta-TG and PF4 levels between AD and psoriasis patients. These results show blood platelet activation in ...