Tolerance Following Peanut Oral Immunotherapy

Clinical Objectives: 1. To evaluate whether PN OIT induces increased tolerance, defined as a statistically significant increase in the median eliciting dose (ED) from a double-blind placebo-controlled food challenge (DBPCFC) before and after treatment with PN OIT and after subsequent allergen avoidance. 2. To evaluate whether PN OIT induces clinical desensitization, defined as 1) a median 10-fold or greater increase in ED at DBPCFC before and after PN OIT treatment period 2) a statistically significant higher median ED at DBPCFC following treatment period between active and control treatment; and 3) a significantly lower frequency of accidental ingestion reactions in active versus control treatment. 3. To evaluate the safety of PN OIT. Mechanistic Objectives: 1. To determine whether PN OIT induces a statistically significant increase in the TCR clonal diversity of Treg populations during active treatment among participants who achieve increased clinical tolerance (Tolerance and Partial Tolerance Groups as defined in clinical endpoints) versus the Treatment Failure Group. 2. To determine whether PN OIT suppresses mast cells by inducing a significant suppression of the median ED on end-point dilution skin testing in actively treated participants by the end of maintenance therapy. 3. To determine whether PN OIT suppresses basophils as defined by a 10-fold suppression of peanut-specific basophil ED in actively treated participants by end of a maintenance period. 4. To determine whether either mast cell or basophil suppression at the end of maintenance therapy is significantly associated with clinical outcomes following avoidance. Exploratory Objectives: 1. To describe the gene expression profiles and clonal diversity of regulatory and effector T cell subsets before and after OIT to better understand the phenotype and ontogeny of these subsets and potentially discover new therapeutic pathways. 2. To engineer human MHC class II tetramers on common HLA backgrounds and map T cell epitopes of the dominant peanut allergens for use in validating earlier findings and for future studies of peanut-specific immune responses in humans.