Molecular Analytical Assessment of Thermally Precipitated α-Lactalbumin after Resolubilization

Diagnosis and Rationale for Action against Cow's Milk Allergy (DRACMA) Guidelines update - III - Cow's milk allergens and mechanisms triggering immune activation

Background

The immunopathogenesis of cow's milk protein allergy (CMPA) is based on different mechanisms related to immune recognition of protein epitopes, which are affected by industrial processing.

Purpose

The purpose of this WAO DRACMA paper is to: (i) give a comprehensive overview of milk protein allergens, (ii) to review their immunogenicity and allergenicity in the context of industrial processing, and (iii) to review the milk-related immune mechanisms triggering IgE-mediated immediate type hypersensitivity reactions, mixed reactions and non-IgE mediated hypersensitivities.

Results

The main cow’s milk allergens – α-lactalbumin, β-lactoglobulin, serum albumin, caseins, bovine serum albumins, and others – may determine allergic reactions through a range of mechanisms. All marketed milk and milk products have undergone industrial processing that involves heating, filtration, and defatting. Milk processing results in structural changes of immunomodulatory proteins, leads to a loss of lipophilic compounds in the matrix, and hence to a higher allergenicity of industrially processed milk products. Thereby, the tolerogenic capacity of raw farm milk, associated with the whey proteins α-lactalbumin and β-lactoglobulin and their lipophilic ligands, is lost.

Conclusion

The spectrum of immunopathogenic mechanisms underlying cow's milk allergy (CMA) is wide. Unprocessed, fresh cow's milk, like human breast milk, contains various tolerogenic factors that are impaired by industrial processing. Further studies focusing on the immunological consequences of milk processing are warranted to understand on a molecular basis to what extent processing procedures make single milk compounds into allergens.

Investigation of an Uncommon Artifact during Reducing Capillary Electrophoresis-Sodium Dodecyl Sulfate Analysis of a Monoclonal Antibody with Dynamic Light Scattering and Reversed Phase High-Performance Liquid Chromatography

PURPOSES

In reducing capillary electrophoresis sodium dodecyl sulfate (CE-SDS) analysis of a monoclonal antibody (mAb-1), the peak area ratio of heavy chain (HC) to light chain (LC) was out of balance, while multiple artifact peaks were observed following the migration of HC. The main purposes of this study were to describe the techniques utilized to eliminate this artifact and clarify the root cause for this interesting phenomenon.

METHODS

We optimized the CE-SDS analysis of mAb-1 by a vairety of techniques including changing the concentration of protein or replacing SDS with a more hydrophobic surfactant (i.e., sodium hexadecyl sulfate (SHS) or sodium tetradecyl sulfate (STS) instead of SDS) in sample and/or the sieving gel buffer. Dynamic light scattering (DLS) and reversed phase high-performance liquid chromatography (RP-HPLC) were used to study the protein-surfactant complex.

RESULTS

The artifact could be partially mitigated by reducing the protein concentration and replacing SDS with SHS or STS in the sample and/or the sieving gel buffer solutions. Due to replacing a more hydrophobic surfactant, the HC-surfactant complex formed was more resistant to dissociation, preventing additional hydrophobic HC-HC interaction and aggregation, thus eliminating the artifact problem.

CONCLUSIONS

DLS and RP-HPLC are powerful supplementary techniques in characterizing the protein-surfactant complex, and hydrophobic surfactants such as SHS and STS could afford more normal electropherograms during the analysis of mAbs.