Increased basal activation status was noted in adult anaphylaxis patients

Background: Anaphylaxis to food, drugs and diagnostic reagents have been increasingly reported in adult patients; however, its pathogenic mechanisms or an efficient diagnostic test have not been settled. Basophil activation test (BAT) using two activation markers, CD203c and CD63, has been readily used to assess basophil activation status. Considering that mast cell/basophil play an important role in anaphylaxis, we evaluated the basophil activation status using CD203c and CD63 expressions in anaphylaxis patients compared to allergic patients without anaphylaxis.

Method: 41 patients with various allergic diseases including asthma/rhinitis, chronic urticaria as well as anaphylaxis and 23 normal healthy controls (NC) were enrolled in the study. Allergic patients were divided into two groups: anaphylaxis (n=13) and non-anaphylaxis groups (n=28), based on the presence of anaphylaxis to different drugs, foods and diagnostic reagents. BAT using CD203c and CD63 expression was performed in baseline and after stimulation with anti-IgE or calcium (Ca²⁺) ionophore. The BAT is based on double staining with anti-CD123 and anti-HLA-DR and subsequent determination of the percentage of activated basophils by flow cytometry.

Results: Baseline % expressions of both CD203c (30.28±23.10 vs. 13.76±14.60, P=0.036) and CD63 (17.67±20.48 vs. 3.31±3.73, P=0.028) on basophils were significantly higher in anaphylaxis group compared to NCs, while no differences were noted in non-anaphylaxis group. When the positive cutoff value for a positive BAT result was defined as mean+2SD of CD203c expression, positive BAT rate tended to be higher in anaphylaxis group (38.46%) than in non-anaphylaxis group (17.85%, P=0.20), while no differences were noted in CD63 expression levels. There were no significant differences in baseline % expressions of CD203c and CD63 or those induced by anti-IgE/Ca²⁺ ionophore according to age, sex, atopic status, total IgE and ECP levels.

Conclusion: These findings suggest that increased basal activation status of basophils may contribute to develop anaphylaxis in adult patients regardless of atopy status, serum total IgE and ECP levels. BATs with applying each allergen will be useful to confirm the causative agent.