Allergen-specific induction of PCIS contractions reflects allergic status of the donor
In order to establish PCIS as a model of FA, responses must be reproducible, allergen-specific, and clinically relevant. PCIS passively sensitized with plasma from clinically confirmed peanut allergic children displayed a strong contractile response after stimulation with PE (Figure 4A; Video S7,8). This response was strictly allergen-specific, as stimulation with a clinically irrelevant food allergen (OVA) did not result in an increased response (Figure 4A; Video S9,10).
To evaluate whether response patterns were linked to allergen-specific IgE or match clinical reactivity at the individual level, PCIS were passively sensitized with plasma from peanut-sensitized non-allergic donors. These donors had measurable peanut-specific IgE but were asymptomatic upon peanut exposure. PCIS sensitized with this plasma did not show significant muscle contraction responses following stimulation with PE, while maintaining reactivity to positive controls (Figure 4A; Video S11, 12). The total AUCs of each contraction response revealed a significantly greater response following stimulation with a relevant allergen (PE), in comparison to an irrelevant allergen (OVA) in slices sensitized with peanut allergic plasma, as well as to PE stimulation in sensitized non-allergic tissue (Figure 4B).
Tryptase was measured in the culture supernatant following stimulation to confirm the release of mast cell derived mediators (Figure 4C). Tryptase concentrations in the supernatant of PCIS were significantly greater following exposure to PE and elevated in response to FcɛRI-crosslinker in tissue sensitized with peanut allergic plasma. Unstimulated tissue or stimulation with an irrelevant allergen (OVA) did not result in similar tryptase levels, demonstrating the specificity of the response and linkage to degranulation (Figure 4C). PE stimulation in slices sensitized with peanut sensitized non-allergic plasma did not result in a significant change in tryptase concentration, reflecting their lack of reactivity to PE exposure (Figure 4C).