Allergic Skin Reactivity and Chemical Properties of Allergens in Two Grades of Lactose

Skin tests of the nondialyzable fraction of lactose were performed on patients with a clinical diagnosis of cow's milk allergy. The yields of brownish-colored residue, allergens (ALG), were 0.006% from reagent grade lactose (ALG 1) and 0.011% from lactose used in a commercial infant food formula (ALG 2). The ALG was separated into four fractions by chromatography on Sephadex G-75. The highest incidences of positive skin reaction among the four ALG 1 and ALG 2 fractions were 8/9 and 8/12 respectively. The ALG fractions were identified as a sugar protein complex and the protein moiety of ALG contained high amounts of glutamic acid (or glutamine), threonin, asparagic acid (or asparagine) and proline.