Stimulation of blood mononuclear cells of atopic children with the relevant allergen induces the release of eosinophil chemotaxins such as IL-3, IL-5, and GM-CSF.

Peripheral blood mononuclear cells (PBMC) from 10 atopic asthmatic children (atopics), sensitized to Dermatophagoides pteronyssinus (Dp), and from 5 nonatopic healthy children (controls) were stimulated with Dp extract or with birch extract (Be). After 6 days we tested the supernatant's (Sn) chemotactic activity toward purified blood eosinbnophils and T-lymphocyte proliferation. Dp induced a statistically significant T-cell proliferation from atopics as compared to controls (p < 0.05), which correlated with the levels of eosinophil chemotactic activity in the Sn (r = 0.713; p < 0.05). Measurable levels of IL-3, IL-5, and GM-CSF were demonstrated in the Sn of Dp-stimulated PBMC from atopics, while eosinophil locomotion toward different concentrations of recombinant human (rh) IL-3, rhIL-5, and rhGM-CSF confirmed that these cytokines were able to stimulate eosinophil chemotaxis in a close concentration range. Preincubation of different concentrations of the same Sn with blocking antisera demonstrated that anti-human (ah) IL-3, ahIL-5, and ahGM-CSF effectively decreased eosinophil chemotaxis (p < 0.05; each comparison). Thus PBMC activation with the relevant allergen induces the release by T cells with a Th2 phenotype of chemotactic factors for eosinophils.