Identification of elastase in human eosinophils: immunolocalization, isolation, and partial characterization

Area of Science:

• Biochemistry
• Immunology
• Cell Biology

Background:

• Eosinophil elastase activity was previously reported in mice but not purified or characterized in mammals.
• Understanding eosinophil enzymes is crucial for inflammatory and immune response research.

Purpose of the Study:

• To isolate and characterize eosinophilic elastase from human eosinophils.
• To compare the properties of eosinophilic elastase with neutrophil and monocyte elastases.

Main Methods:

• Isolation of eosinophilic elastase from human eosinophil fragments (cytosomes).
• Purification to electrophoretic homogeneity using fast protein liquid chromatography (FPLC).
• Biochemical characterization and reaction with monoclonal antibodies against human neutrophil elastase.

Main Results:

• Eosinophilic elastase was successfully isolated and purified from human eosinophils.
• The purified enzyme exhibited identical physical properties to the major elastase isoenzyme of human neutrophils.
• Eosinophilic elastase cross-reacted with a monoclonal antibody specific for human neutrophil elastase.
• Immunolocalization revealed the enzyme in both types of dense cytoplasmic granules within eosinophils.

Conclusions:

• Human eosinophils and neutrophils share the same elastase enzyme activity.
• This finding supports the hypothesis that eosinophil granules represent stages of maturation.
• Eosinophilic elastase plays a role in inflammatory processes and warrants further investigation.