Priming-like effect and successful desensitization after anaphylactic shock by latex sublingual immunotherapy.

ABSTRACT

The present report deals with some unusual events observed restarting allergy vaccine in a case of anaphylactic shock which occurred giving the maximum scheduled dose (25 drops) of rush sublingual immunotherapy (SLIT) to latex. Restarting SLIT by usual (not rush) scheme we observed long-lasting fall of reactivity threshold. The maximum tolerable dose was reduced to 2 drops, a dose fivefold smaller than the one well tolerated during previous rush phase (10 drops). We have excluded a possible nocebo effect and proved that the reduced tolerance was real by double blind placebo-controlled challenge test. We have considered this effect in some ways similar to priming effect. SLIT was continued with two drops every day. After about twenty months we could demostrate a significant reduction of skin reactivity by end-point technique and an improved response to the controlled exposition to latex by use-tests. In the same time the tolerance to vaccine was improved to three drops. The better safety profile allowed us to restart and continue with SLIT also in the reported case of anaphlicatic shock by latex vaccine and, after about two years, to induce valuable hyposensitization. Latex SLIT is confirmed as a safe and effective method.