Food Sublingual Immunotherapy Using Consistent, Cheaper and Customizable Oral Immunotherapy Solutions

Food Sublingual Immunotherapy (SLIT) is a food desensitization method with a typical daily maintenance dose of <10 mg protein for up to 3–5 years, which has been shown to increase tolerance in hazelnut and peanut allergic patients in randomized, double-blind, placebo-controlled trials.^1,2 In SLIT, intact food protein is given sublingually to the tolerogenic antigen-presenting Langerhans cells, held for 2 minutes, and then swallowed or spat out. Starting doses are at the microgram level and increase to milligram doses by maintenance.³ SLIT buffers against unintentional food exposure while maintaining a favorable safety profile with mostly transient oropharyngeal itching in less than 5% of peanut SLIT doses.⁴ Many published SLIT protocols use commercially available skin test extracts.

Skin test extracts have relatively higher protein concentration variability and cost, and lower customizability in comparison to Oral Immunotherapy (OIT) solutions. Egg and milk skin test extracts contain 2–4 mg protein per milliliter, while peanut extract contains 4–8 mg protein per milliliter at an approximate price of 4 US dollars per mg protein.⁵ Allergists collaborate to develop and refine OIT protocols which yield solutions with reasonable protein concentration consistency.^6,7 Since actual food is used to make OIT solutions, the cost is orders of magnitude less. Although OIT solutions have a shorter shelf life than skin test extracts, they can be frozen for future use.⁸ An OIT solution can be made to approximate the protein concentration of a skin test extract and substituted for the skin test extract used in a published SLIT protocol⁴ (Figure 1) and is found to dispense easily (Figure 2). If for any reason, the maintenance dose needs to be adjusted, the OIT solution can be customized without changing the protocol, which is difficult to do with skin test extracts which have variable, fixed protein concentrations (Table 1).

Table 1 Summary of Food Amounts Needed to Create a SLIT Maintenance Vial Using an OIT Dosing Protocol

Figure 1 Food SLIT dilution protocol.

Figure 2 Peanut dilution 1 – 1:1 5mg/mL plus flavoring.

We hope that this adaption of OIT solutions for use in available SLIT protocols improves the access to consistent, economical, and customizable food desensitization.