Basophil Status Doesn't Predict Immunotherapy Response

Activation not tied to efficacy of sublingual grass pollen allergy immunotherapy, adverse events

WEDNESDAY, Nov. 2 (HealthDay News) -- Peripheral blood basophil activation is not associated with efficacy of sublingual immunotherapy (SLIT) to grass pollen, nor is it predictive of adverse events or early onset of clinical responses, according to a study published in the December issue of Allergy.

Laurence Van Overtvelt, Ph.D., from Stallergenes in Antony, France, and colleagues evaluated the safety and efficacy of SLIT in 89 patients with allergic rhinoconjunctivitis to grass pollen. Participants received either a placebo or a five-grass-pollen tablet sublingually daily for four months. They were exposed to an allergen challenge chamber, and their individual rhinoconjunctivitis total symptom scores (RTSS) were calculated to identify clinical responders and nonresponders. Activation of peripheral blood basophils was assessed before starting immunotherapy, and after two or four months.

The investigators found that, after four months of SLIT, patients receiving the grass-pollen tablet showed a significant relative mean improvement of 29.3 percent in the average RTSS versus those receiving placebo. Despite induction of specific immunoglobulin (Ig) Gs, there were no significant changes in basophil activation after two or four months of SLIT. Basophil activation in clinical responders was either decreased, increased, or unmodified during SLIT. Local adverse reactions associated with immunotherapy were not predicted by the pre-immunotherapy levels of basophil activation. Basophil activation was moderately associated with allergen-specific IgE levels, skin reactivity, or RTSS.

"Allergen reactivity of peripheral blood basophils is not a biomarker for adverse events or early onset of clinical responses to SLIT," the authors write.

Several authors disclosed financial relationships with Stallergenes SA, which provided the allergens for the basophil activation tests.

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