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).