D1.290 - Identification of a Cheese-Derived κ-Casein Fragment as the Trigger of Anaphylaxis in a Patient with Suspected Pasta Allergy

Adverse reactions attributed to cereal-based foods may mask sensitization to hidden or processed ingredients. Pasta dishes frequently contain dairy products, whose protein modification during food processing can generate new epitopes with allergenic potential. We report a case of anaphylaxis, initially associated with pasta consumption, investigated through immunochemical and proteomic approaches to identify the culprit allergen.

A 29-year-old patient experienced recurrent episodes of anaphylaxis after ingestion of Italian pasta dishes, while tolerating bread. Skin prick testing with commercial flour extracts and peach was negative. Protein extracts were prepared from wheat flours (type 1 and 00), raw and cooked pasta, sauces (cacio e pepe and egg-based), and cheeses (stracciatella and mozzarella Fior di Latte). IgE reactivity was assessed by SDS-PAGE and IgE–Western blot using patient serum. Inhibition Western blot assays were performed with cow’s milk and between cheese extracts to assess cross-reactivity. The IgE-reactive band was subjected to LC-MS/MS proteomic analysis.

IgE–Western blot showed no IgE binding to wheat flours, pasta (raw or cooked), or sauces. In contrast, both cheese extracts demonstrated a consistent IgE-reactive band at approximately 15 kDa. Western blot with cow’s milk and inhibition assays using milk as inhibitor were negative, excluding native milk proteins as the direct allergen. Inhibition Western blot between stracciatella and mozzarella extracts demonstrated complete mutual inhibition, indicating shared IgE-binding epitopes. Proteomic analysis of the IgE-reactive band identified a fragment of κ-casein. The lack of IgE recognition in whole milk suggests that the allergenic epitope is conformational and generated during cheese processing, likely through proteolytic fragmentation and physicochemical changes.

This case demonstrates IgE-mediated anaphylaxis caused by a cheese-derived κ-casein fragment. Food processing can generate allergenic protein fragments not present or not immunoreactive in the native source. This report highlights the importance of considering processed food components in unexplained food-induced anaphylaxis.