Clinical and laboratory 2‐year outcome of oral immunotherapy in patients with cow's milk allergy

Studies examining the long-term effect of oral immunotherapy in food-allergic patients are limited. We investigated cow's milk-allergic patients, >6 months after the completion of oral immunotherapy (n = 197). Questionnaires, skin prick tests, and basophil activation assays were performed. Of the 195 patients contacted, 180 (92.3%) were consuming milk protein regularly. Half experienced adverse reactions, mostly mild. Thirteen patients (6.7%) required injectable epinephrine. Higher reaction rate after immunotherapy was associated with more anaphylactic episodes before treatment and a lower starting dose (OR = 2.1, P = 0.035 and OR = 2.3, P = 0.035, respectively). Reaction rate in patients who were 6-15 months, 15-30 months, or >30 months post-treatment decreased from 0.28/month to 0.21/month to 0.15/month, respectively (P < 0.01). Milk-induced %CD63 and %CD203c expression was significantly lower in patients >24 months vs in patients <24 months post-treatment (P = 0.038 and P = 0.047, respectively). In conclusion, many patients experience mild adverse reactions after completing oral immunotherapy and some require injectable epinephrine. Progressive desensitization, both clinically and in basophil reactivity, occurs over time.