In vitro Interaction between Human Basophils and Polymorphonuclear Granulocytes Effect of Airborne Particulate Matter

The effects of extracts of airborne particulate matter (APM) on morphology and mediator release from enriched basophils (HBC) and from purified neutrophils of pollen-allergic and nonallergic individuals were investigated. APM was collected on glass fiber filter sheets using high volume samplers HVS150. After preparing an aqueous extract, in which allergens are absent, followed by extraction of organic substances, the mediator-releasing activity of the APM extracts was studied under defined and physiological in vitro conditions. The results indicate that APM potentiates anti-IgE-induced histamine release (HR) and that this enhancement is significantly higher in HBC samples from pollen allergic donors than from nonallergic individuals. Electronmicroscopy of APM-exposed HBC reveals basophil degranulation in addition to strong activation of platelets and neutrophils, the latter sticking onto the surface of HBC and forming clusters with them. Incubation of purified PMN with APM prior to zymosan stimulation showed that these substances also enhance the release of LTB4, LTC4, PGE2 and IL-8. The results show that substances adsorbed to APM interfere with mediator cells of the allergic inflammation and exhibit 'priming' effects on them. Therefore, exposure of individuals to high concentrations of APM can provoke enhancement in symptoms of allergy and continuation of allergic inflammation.