Kirsi-Marjut Järvinen

IgE and IgG Binding Epitopes on α-Lactalbumin and β-Lactoglobulin in Cow’s Milk Allergy

Background: Cow’s milk is one of the most common causes of food allergy in the first years of life. We recently defined IgE and IgG binding epitopes for αs1-casein, a major cow’s milk allergen, and found an association between recognition of certain epitopes and clinical symptoms of cow’s milk allergy (CMA). Since α-lactalbumin (ALA) and β-lactoglobulin (BLG) are suspected to be significant allergens in cow’s milk, we sought to determine the structure of sequential epitopes recognized by IgE antibodies to these proteins. We further sought to assess the pattern of epitope recognition in association with the clinical outcome of CMA. Methods: According to the known amino acid sequence of ALA and BLG, 57 and 77 overlapping decapeptides (offset by two amino acids), respectively, were synthesized on a cellulose derivatized membrane. Sera from 11 patients 4–18 years of age with persistent CMA (IgE to cow’s milk >100 kUA/l) were used to identify IgE binding epitopes. In addition, 8 patients <3 years of age and likely to outgrow their milk allergy (IgE to cow’s milk <30 kUA/l) were used to investigate the differences in epitope recognition between patients with ‘persistent’ and those with ‘transient’ CMA. Seven patients 4–18 years of age were used for assessing the IgG binding regions. Results: In patients with persistent allergy, four IgE binding and three IgG binding regions were identified on ALA, and seven IgE and six IgG binding epitopes were detected on BLG. The younger patients that are likely to outgrow their allergy recognized only three of these IgE binding epitopes on BLG and none on ALA. Conclusions: The presence of IgE antibodies to multiple linear allergenic epitopes may be a marker of persistent CMA. The usefulness of IgE binding to distinct epitopes on whey proteins in defining the patients that would have a lifelong CMA needs to be investigated in further studies.

Identification of Sequential IgE-Binding Epitopes on Bovine αs2-Casein in Cow’s Milk Allergic Patients

Background: Caseins are the major allergens responsible for cow’s milk allergy (CMA). We have previously identified the IgE-binding epitopes of the major cow’s milk (CM) proteins except for αs2-casein. Methods: Overlapping decapeptides representing the entire length of αs2-casein were synthesized on a cellulose-derivatized membrane. Sera from 13 CM-allergic children, 4–15 years of age, with a median level of CM-specific IgE >100 kU/l (range 33.7 to > 100 kU/l) were used to identify IgE-binding epitopes. Results: Four major and six minor sequential IgE-binding regions were identified on αs2-casein. The first major region is located in the middle of the protein at amino acids (AA) 83–100, and the other three major regions are located in the carboxy terminal portion of the protein at AA 143–158, 157–172 and 165–188. The minor IgE-binding regions were identified at AA 31–44, 43–56, 93–106, 105–114, 117–128, and 191–200. Conclusion: We identified 10 sequential IgE-binding regions on αs2-casein and performed the first crucial step in the development of immunotherapeutic interventions for CMA.

Mutational analysis of immunoglobulin E‐binding epitopes of β‐casein and β‐lactoglobulin showed a heterogeneous pattern of critical amino acids between individual patients and pooled sera

Background For immunotherapeutic approaches, ‘critical’ amino acids (AAs) within allergenic epitopes are replaced with alternate AAs to eliminate IgE antibody binding.

Identification of amino acids critical for IgE-binding to sequential epitopes of bovine κ-casein and the similarity of these epitopes to the corresponding human κ-casein sequence

Background:  The delineation of allergenic (i.e. IgE‐binding) epitopes in cow’s milk proteins and the amino acids (AAs) critical for IgE‐binding is necessary to understand better the structural properties of an allergen and to develop more efficacious immunotherapeutic reagents. Furthermore, this information may enable us to understand better cross‐sensitivity between different allergens.