Peanut oral immunotherapy modifies IgE and IgG4 responses to major peanut allergens.

Background Patients with peanut allergy have highly stable pathologic antibody repertoires to the immunodominant B-cell epitopes of the major peanut allergens Ara h 1 to 3. Objective We used a peptide microarray technique to analyze the effect of treatment with peanut oral immunotherapy (OIT) on such repertoires. Methods Measurements of total peanut-specific IgE (psIgE) and peanut-specific IgG 4 (psIgG 4 ) were made with CAP-FEIA. We analyzed sera from 22 patients with OIT and 6 control subjects and measured serum specific IgE and IgG 4 binding to epitopes of Ara h 1 to 3 using a high-throughput peptide microarray technique. Antibody affinity was measured by using a competitive peptide microarray, as previously described. Results At baseline, psIgE and psIgG 4 diversity was similar between patients and control subjects, and there was broad variation in epitope recognition. After a median of 41 months of OIT, polyclonal psIgG 4 levels increased from a median of 0.3 μg/mL (interquartile range [25% to 75%], 0.1-0.43 μg/mL) at baseline to 10.5 μg/mL (interquartile range [25% to 75%], 3.95-45.48 μg/mL; P de novo specificities. psIgE levels were reduced from a median baseline of 85.45 kU A /L (23.05-101.0 kU A /L) to 7.75 kU A /L (2.58-30.55 kU A /L, P 4 binding occurred, including at an informative epitope of Ara h 2. Conclusion OIT differentially alters Ara h 1 to 3 binding patterns. These changes are variable between patients, are not observed in control subjects, and include a progressive polyclonal increase in IgG 4 levels, with concurrent reduction in IgE amount and diversity.