Hydrolysis and peptide profiling crucial for the choice of hypoallergenic milk protein formula suitable for tolerance induction and primary prevention of allergic sensitisation

Background: Hypoallergenic cow's milkbased formulas containing protein hydrolysates are usually used to prevent reactions in cow's milk allergic infants. Early exposure to small immunogenic and toleranceinducing peptides is further suggested to prevent allergy development. In this study, we compared the hydrolysates from two whey protein sources, both potentially containing small immunogenic fractions, in their capacity to prevent early sensitisation to cow's milk proteins (CMP). Method: Five-Week old naïve C3H/HeOuJ mice were treated with two whey protein sources (Whey 1 and Whey 2, as positive controls for oral tolerance induction) or their corresponding hydrolysates (WH1 and WH2, respectively) prior to sensitisat-ion. Mice were then sensitised orally with Whey 1 or Whey 2 mixed with cholera toxin as adjuvant. One week after the last sensitisation, mice were intradermally and orally challenged with whey protein. Clinical symptoms such as anaphylactic shock and body temperature were determined. Furthermore, serological analysis of allergen-specific IgE and IgG1 and mouse mast cell protease 1 (mMCP-1) were performed. Results: Prior exposure to whey protein prevented the development of clinical allergic symptoms as no anaphylactic shock and drop in body temperature were observed in those groups. Both hydrolysates were not able to prevent allergy development to whey, however, WH1 tended to lower mMCP-1. By contrast, pretreatment with WH2 resulted in significantly more whey-IgE and mast cell degranulation. The same pattern was observed for whey-IgG1 levels. Conclusion: Whey protein prevented the development of clinical symptoms of allergy, reflecting the expected tolerance induction. Reduction in size of CMP in hydrolysates might be sufficient for secondary (challenge) prevention, but potential differences in the characteristics of the resulting peptides might determine whether a hydrolysate will possess tolerogenic or allergenic capacities further highlighting the necessity of proper peptide profiling.