Markers of platelet activation in plasma of patients suffering from persistent allergic rhinitis with or without asthma symptoms

BACKGROUND: Increased circulating levels of platelet release products are detected in various types of inflammation. It has been demonstrated that allergen challenge promotes platelet activation and leads to the release of chemokines such as platelet factor 4 (PF-4) and beta-thromboglobulin (beta-TG). OBJECTIVE: The aim of this study was to determine whether or not circulating platelets get into an activated state during allergic inflammatory reactions induced by long-term natural exposure to allergens. METHODS: Plasma levels of PF-4 and beta-TG (established markers of in vivo platelet activation) were determined by ELISA method in symptomatic patients with allergy to house dust mites, suffering from persistent allergic rhinitis (PAR) in the absence of asthma symptoms (12 men and 8 women; mean age 22 years) and from PAR with mild asthma (10 men and 6 women; mean age 23 years), as well as in healthy controls (10 men and 10 women; mean age 23 years). RESULTS: No significant differences were found between PAR patients with or without symptoms of asthma and healthy non-atopic subjects with respect to plasma levels of PF-4 and beta-TG as well as platelet count. CONCLUSIONS: It seems that patients undergoing continuous natural exposure to sensitizing allergens, with subsequent PAR alone or with concomitant mild asthma, have no altered platelet activity in vivo, as reflected by plasma levels of the chemokines. These findings, in conjunction with earlier data, indicate that differences may exist in platelet activity, including releasability of platelet products between patients with distinct clinical manifestation of atopy.