A combinatory approach of negative IgE to PVs and extracts
allows stratifying the patients for tolerance-confirming FC with bony or
cartilaginous fish
At last, the proportion of the patients who may tolerate specific fish
was investigated, based on negative in vitro IgE tests to PV, RE
and HE. Between 60% (Spain) and 90% (Luxembourg) of the patients were
negative to ray PV, RE and HE (Figure 5A) . The percentage of
the patients negative to each tested bony fish varied across the
countries and up to 21% of the patients (mackerel, Denmark) were
negative to one or more bony fish. For the cohorts from Austria,
Denmark, Luxembourg and Norway, all tested species were found to be
potentially tolerated by some patients. Only ray and herring were shown
to be the potentially tolerated in the Chinese cohort, while for Spain,
except for tuna, IgE tests to all other species were negative for some
patients (Figure 5A ). All patients negative to PV, REs and HEs
from specific species are listed in Table SIV . Based on these
findings, 8 patients underwent prick-to-prick (PPT) with ray
(Dipturus innominatus available in China), of which 6 showed skin
reactivity neither to raw nor to cooked ray. These patients are
candidates for future FCs to confirm their clinical tolerance. The
patients with absence of reactivity to ray by PPT are labelled with an
asterisk (*) in Table SIV .
Figure 5B shows the probability that all 3 IgE tests (to PV, RE
and HE) are negative for species X (x-axis) if negative for species Y
(y-axis). These data can be used to predict possible tolerance of
specific species if tolerance of others is known. Negativity to tuna and
mackerel showed the highest likelihood of negativity not only to ray but
also to other bony fish. Specifically, patients negative to tuna have
92% probability to be negative to ray and swordfish. If negative to
mackerel, 93% chance exists to be negative to herring and ray, and 86%
to swordfish. However, if negative to salmon or swordfish, the
probability of IgE tests to be negative to other bony fish is ≤58%.