Ex vivo and in vivo cross-reactivity between major and minor allergens from cow's milk: A study in Balb/c mouse model

Abstract

Study objective

It is well known that proteins that belong to the same family are often associated with frequent cross-reactivities. To the best of our knowledge, this is the first study evaluating the cross-reactivity between bovine lactoferrin (bLf) and the two major bovine milk allergens, β-lactoglobulin (β-Lg) and α-lactalbumin (α-La).

Materials and methods

Five-to six-week-old female Balb/c mice were randomly allocated to three groups (n = 14 per group) as follows: control group (unsensitized mice), β-lactoglobulin-sensitized group and α-lactalbumin-sensitized group. Mice were sensitized by intraperitoneal injection of 10 μg of allergen conjugated with aluminum hydroxide. Cross-reactivity was tested in vitro using an enzyme-linked immunosorbent assay, ex vivo by measuring electrophysiological parameters [short-current circuit (Isc) and tissue conductance (G)] in an Ussing chamber system and finally in vivo after an intraperitoneal challenge with bLf. Plasma histamine levels were also measured.

Results

bLf was found to significantly cross-react with either anti β-lg or anti α-La IgG with different intensities. Notably, the anti α-La IgG was more cross-reactive (P < 0.001). In Ussing chamber, the ex vivo exposure of intestinal segment of the two-sensitized groups to bLf induced a marked increase in Isc values (P < 0.05 and P < 0.006 respectively). However, the tissue conductance was increased only with the jejunal fragments of α-La-sensitized mice (P < 0.05). bLf cross-reactivity was also evidenced clinically by the appearance of clinical symptoms, as well as a significant increase in plasma histamine levels (P < 0.001).

Conclusion

bLf exhibits a strong allergenic potential and a high degree of homology, especially with α-La.