Effect of allergen-specific immunotherapy on plasma level of platelet factor 4 (PF-4) and beta-thromboglobulin (beta-TG), platelet activation markers in patients with house dust mite allergy.

Patients suffering form house dust mite-sensitive persistent allergic rhinitis (PAR) seem to show changed platelet aggregability following mite allergen-specific immunotherapy (SIT). However, in patients with grass pollen-sensitive intermittent allergic rhinitis, platelet release reaction in vivo, measured by beta-TG, did not change significantly during the dose increase phase of subcutaneous SIT with grass pollen allergoids. The aim of this study was to evaluate the influence of SIT with house dust mite allergen extracts on the degree of circulating platelet activity in patients with PAR. The study comprised 14 patients sensitized to house dust mite allergens with PAR during the early phase of subcutaneous SIT with house dust mite allergen extracts-Dermatophagoides farinae 50 p.c. and Dermatophagoides pteronyssinus 50 p.c. (Novo-Helisen Depot, Allergopharma, Germany). SIT comprised subcutaneous injection of allergen extracts during approximately 3 months. Blood was collected before SIT, as well as immediately before, 30 min and 24 h after maximum dose injection. Plasma levels of PF-4 and beta-TG, platelet activation markers were measured using commercial ELISA kit. PF-4 and beta-TG basal levels were not significantly different between the patients and the healthy subjects. PAR patients treated with SIT showed no significant differences in plasma levels of the markers between the different points of the study. Thus, it seems that the degree of platelet activation measured by PF-4 and beta-TG does not change in PAR patients during hyposensitization with mite allergen extracts, after the maximum dose was reached.