Immune response and clinical reaction to milk protein in an adjuvant‐free mouse model of milk allergy

Abstract

Milk allergy is a major type of food allergy with potential for life threatening anaphylactic reaction. Mechanism of sensitization to milk protein is incompletely understood at present. Here we tested the hypothesis that transdermal exposure to milk protein, without an adjuvant, is sufficient to sensitize mice for milk allergy. All mice were on a diet (NIH 5K52) free of milk protein. Thus, repeated transdermal exposure of BALB/c mice (n=10 per group) to milk protein (Greer Lab's cow milk protein extract) resulted in a robust IgG1 but a modest IgG2a response. However, IgE response was very modest even after six transdermal exposure to milk protein. Nevertheless, oral challenge of sensitized mice but not saline control mice with milk protein resulted in clinical symptoms of systemic anaphylaxis by 1 hour post‐challenge. Furthermore, oral challenge also resulted in hypothermia as measured by a drop in rectal temperature at 30 minutes post‐challenge. These data demonstrate for the first time that: (i) transdermal exposure to milk protein results in a modest allergic response; and (ii) oral challenge of sensitized mice results in an immediate hypersensitivity reaction characterized by systemic anaphylaxis. Funding: US EPA STAR#R833133