Severe egg allergy treatment shows promise

By Helen Albert, Senior medwireNews Reporter

Specific oral tolerance induction (SOTI) with raw hen's egg can reduce the severity of egg allergy in affected children, show study findings.

The researchers found that gradual addition of increasing amounts of raw egg emulsion into flavored milk on 32 occasions over 176 days led to 90% of the children achieving at least partial tolerance to raw hen's egg.

"Introduction of baked egg may increase tolerance in egg-allergic patients, but tolerance to extensively heated egg is not predictive of clinical reactions to regularly cooked or raw egg," explain Salvatore Tripodi (Sandro Pertini Hospital, Rome, Italy) and colleagues.

They therefore initiated a SOTI trial in which increasing amounts of raw hen's egg were added to flavored infant formula milk. Twenty children aged 5 to 11 years were enrolled in total, 10 of whom were randomized to the intervention and 10 to a control group (flavored formula milk with no egg). The intervention took place over 6 months and a second challenge took place 6 months after the intervention was completed.

At completion of the intervention, nine of the 10 children in the intervention group achieved partial tolerance to hen's egg (at least 10, but less than 40 ml in one dose with only minor side effects), and one had no tolerance (could only tolerate 5 ml maximum).

At the second challenge, nine children in the control group tested positive to 0.9 ml raw hen's egg or less and one reacted to 1.8 ml raw hen's egg.

Although side effects were common in the children in the SOTI intervention group (eg, rhinitis, oral pruritus, and abdominal pain), none had a Sampson grade 5 reaction (most severe allergic reaction with symptoms including respiratory arrest, cardiac arrest, or loss of consciousness).

"None of our patients reached maximum tolerance. However, tolerance was achieved at doses higher than those associated with anaphylaxis from accidently ingested hen's egg," says the team.

"It remains to be established whether to prolong the time required to reach tolerance or to risk more reactions in order to achieve tolerance, albeit partial, sooner," they add in Pediatric Allergy and Immunology. "Follow-up will show whether tolerance acquirement is permanent," they conclude.

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