It has been appreciated for many years that food allergy was associated with an allergen-specific type 2 cytokine profile, defined by production of IL-4, IL-5, and IL-13 from CD4+ T cells. Initial studies grew lines from patient-derived PBMCs, and demonstrated type 2 cytokine production from the lines (de Jong et al., 1996; Higgins et al., 1995). CFSE-labeling of peanut-reactive T cells indicated an abundance of IL-4, IL-5, and IL-13 producing T cells from peanut allergic donors compared to donors who had outgrown their peanut allergy (Turcanu et al., 2003). Growing lines or allowing cells to proliferate in culture can alter the phenotype of responder cells. Studies using activation marker-based approaches to identification of allergen-specific CD4+ T cells that examined the cytokine phenotype after as little as 4–6 h of stimulation ex vivo showed a robust Th2 skewing of T cells from peanut or egg allergic individuals (Berin et al., 2018; Chiang et al., 2018; Prussin et al., 2009; Ruiter et al., 2020; Wambre et al., 2017). Controls who were sensitized but not reactive, or healthy controls, showed a much reduced frequency of antigen-specific T cells and a lack of type 2 skewing (Chiang et al., 2018; Prussin et al., 2009). In addition to IL-4, IL-5, and IL-13, IL-9 has been identified as an important CD4+ T cell cytokine associated with the peanut-specific immune response (Brough et al., 2014; Chiang et al., 2018). Type 2 T cells were shown to be highly differentiated memory T cells, expressing multiple type 2 cytokines (IL-4, IL-5, IL-13, IL-9) and lacking expression of CD27 (Chiang et al., 2018; Wambre et al., 2017). One subset of highly differentiated type 2 cells co-express CRTH2, CD49d, and CD161 and have been termed Th2A cells (Wambre et al., 2017). Others have referred to the cells as pathogenic effector Th2 cells, and variably described CRTH2 expression on the cells (Chiang et al., 2018; Monian et al., 2022; Prussin et al., 2009; Ruiter et al., 2020). For simplicity, we will refer to highly differentiated multi-cytokine producing type 2 CD4+ T cells as peTh2. Type 2 cells express CCR4, while CCR6 expression on peanut- or egg-specific T cells negatively correlates with IL-4 and IgE production (Berin et al., 2022).