High sensitivity of basophils predicts side-effects in venom immunotherapy

Systemic side-effects of venom immunotherapy (VIT) represent a considerable problem in the treatment of patients allergic to Hymenoptera venom. We examined the hypothesis whether basophil responsiveness might be connected with the adverse reactions to VIT.

Basophil surface expression of activation marker CD63 induced by different concentrations of honeybee and wasp venom (0.1 and 1 mug/ml) was measured by flow cytometry in 34 patients with history of systemic anaphylactic reactions to Hymenoptera sting just before rush honeybee or wasp VIT.

Eleven of 34 patients had systemic anaphylactic reaction (Mueller grades I-III) and one patient a large local reaction to VIT. In those 12 patients, median percentage of activated basophils after stimulation with VIT-specific venom in concentration of 0.1 microg/ml was 99% (range: 17-195) of value reached with stimulation with 1 microg/ml. Side-effects occurred in all patients with 0.1/1 ratios over 92% (eight of 12). In contrast, in 22 patients with no side-effects, the median 0.1/1 ratio was 25% (range: 2-92). These concentration-dependent activation ratios were significantly different between the groups with and without side reactions (P < 0.0001). We also show significant positive correlation of the occurrence/clinical grade of the side-effects with individual ratios of CD63 basophil response (r = 0.73, P < 0.0001).

The results suggest that increased basophil sensitivity to allergen-specific in vitro stimulation is significantly associated with major side-effects of VIT.