Correct diagnosis of latex-allergy and distinction from latex-sensitization is a major task to prevent serious, potentially fatal reactions to latex, especially during diagnostic and operative procedures. In case of positive specific IgE’s against latex the intriguing challenge is to distinguish between simple sensitization and clinically relevant sensitization, i.e. latex-allergy.
Latex-allergy is mostly attributed to sensitization to Hev b5 and Hev b6. As for Hev b8 sensitized persons, mono-sensitization was seen more often than poly-sensitization to latex-specific allergens. The most serious allergic reactions with intra-operative anaphylaxis were seen in Hev b6 sensitized patients. In spite of having included healthcare workers we did not identify a single person positive to Hev b7, in contrast to Bernstein et al. .
The majority of latex-sensitized persons have a profilin-sensitization with mono-sensitization to Hev b8. Typically, these patients have a positive IgE CAP against latex, but are negative in SPT. In accordance with previous studies, Hev b8 mono-sensitized persons did not show latex-specific symptoms upon contact with latex-containing material in our study apart from one case [16, 18, 19]. The only symptoms reported in some cases were questionable or mild oral symptoms upon contact with food, e.g. kiwi or banana . Thus one could speculate that in sensitization to Hev b8 the latex profilin might partly cause latex-fruit syndrome. This observation has been described in other studies .
The fact that two Hev b8 mono-sensitized persons were positive to bromelain (CCD) and showed symptoms upon contact with latex (contact urticaria/pruritus) raised the question whether antibodies to CCD play a major role in latex-allergy. The role of CCD is also under debate for relevant cross-reactive reactions in bee and wasp allergy or in certain unexplained allergic reactions to food.
We could show that IgE latex CAP has a high sensitivity for detection of latex-sensitized persons, whereas SPT is less sensitive but more specific in our limited patient collective for clinically relevant allergic symptoms. In accordance with other studies IgE latex CAP had high sensitivity but low specificity [4, 21, 22].
A limiting factor of our study is that no component-resolved diagnosis was possible for Hev b12 (lipid-transfer-protein) and for Hev b13. These might also play a role in latex-sensitized persons and be an explanation for the single case of mono-sensitized Hev b8 with symptoms upon contact [17, 23]. However, in atopic patients with repeated regular exposure contact-dermatitis to latex due to late-type-sensitization as well as contact-sensitization to other substances like thiuram should be in- or excluded.
2/4 patients with discordant negative ISAC-results compared to positive ImmunoCAP test that must be considered true latex-allergic were not identified by component resolved diagnosis. The supplementation of additional recombinant latex-allergens to ISAC might enhance sensitivity of the test. However further testing concerning sensitivity of the new microarray-method compared to conventional Cap IgE is advisable.
Our study provides strong evidence that latex-allergy cannot be excluded by simply prick-testing latex. However, a positive SPT should be considered relevant as seen in our study due to high specificity, which can be explained not only by the method but also due to the fact that the prick-test-solution contains Hev b1,3,5,6 but not Hev b8.
In case of positive CAP IgE latex with negative latex SPT (or where no SPT is available), component-resolved diagnosis provides further information.
Development of a tailored biochip containing recombinant latex-allergens Hev b1,3,5,6,7,8,9,10 and bromelain might be a cost-effective variant to conventional IgE measurement in patients positive for Cap IgE latex and negative latex SPT or where latex SPT is not available.