Variations of serum eosinophil cationic protein and tryptase, measured in serum and saliva, during the course of immediate allergic reactions to foods

Background: Subjective complaints and reactions after placebo administration during food challenges (FC) may make their outcome difficult to interpret. We determined serum ECP and tryptase as tryptase in saliva during FC, looking for markers to support challenge outcomes. Methods: Twelve patients with systemic reactions after food intake and nine presenting oral allergy syndrome (OAS) underwent skin tests; total and specific IgE determination; double-blind, placebo-controlled FC (DBPCFC); and open challenges. Blood samples were collected before and 1, 2, and 5 h after challenge and saliva before and 5, 30, and 60 min after challenge. ECP and tryptase were quantified by ImmunoCAP (Pharmacia-Upjohn, Sweden). Serum tryptase of > 10 μg/l was considered positive. Results: After positive DBPCFC (n = 8), ECP rose significantly (P < 0.05) at 1-h -16.03 (12.8) μg/l (mean [standard deviation]) - and 2-h intervals - 17.56 (10.7) μg/l compared to basal level of 9 (6.4) μg/l. After negative DBPCFC (n = 6), ECP increased from basal 9.63 (3.9) μg/l to 24.84 (14.17) μg/l at the 2-h time point. There were nonsignificant differences in ECP between patients with positive and negative FC. Two patients with positive challenge showed a tryptase level of > 10 μg/l and only one patient with OAS showed 5.6 μg/l of tryptase 5 min after FC. Conclusions: ECP and tryptase in serum and saliva were not useful markers for FC outcomes.