Milk and Egg Derived from Different Species Differ in their Reactivity with Allergen Detection Immunoassays

• Buffalo milk and buffalo milk products showed % reactivities of ≥ 41%. • Camel milk and ostrich egg were detected with very low reactivities. • Casein and ovalbumin are the major proteins involved in the antibody binding. In the United States, milk and egg are regulated as major food allergens per the allergen labeling requirements of the Food, Drug, and Cosmetic (FD&C) Act. Clinical cross-reactivity has been reported between chicken eggs and eggs from other fowl and cow’s milk and milk from other ruminant sources. However, there are no published studies on analytical cross-reactivity for commercial immunochemical assays. This study evaluated milk and egg specific enzyme-linked immunosorbent assay (ELISA) methods, and the xMAP Food allergen Detection Assay (FADA) for their ability to detect and quantify milk proteins from buffalo, goat, sheep, and camel milk, and egg proteins from quail, duck, and ostrich egg. Results showed that the Morinaga milk (Casein) ELISA, the Veratox Total milk ELISA, and the xMAP FADA were able to detect buffalo milk and buffalo milk products with % reactivities of ≥ 41% compared to cow’s milk; however, low level detection was observed for sheep, goat, and camel milk. Reactivities compared to the cow’s milk were 1-17% for goat and sheep milk. Camel milk resulted in either a