Identification of a Major Basic Protein in Guinea Pig Eosinophil Granules

Abstract

Elucidation of the functions of the eosinophil might be accomplished by analysis of the granule constituents. We have purified eosinophils (93% or greater) from the peritoneal cavity of the guinea pig and have investigated a variety of methods to disrupt cells and liberate intact granules. Lysis in 0.34 M sucrose gave the best yield of granules and these had the characteristic morphology of eosinophil granules when examined by electron microscopy. Granules were solubilized by a variety of treatments and the solutions analyzed by polyacrylamide electrophoresis at pH 3 in 6 M urea. Comparison of the electrophoretic patterns of solubilized eosinophil and neutrophil granules revealed a difference: a major portion (53±3%; x ±1 SE) of the protein from the eosinophil granule migrated as a single component. This major band protein has a molecular weight between 6,000 and 12,000 daltons and a pI of 10 or greater. Analysis of eosinophil granule constituents on Sephadex G-50 revealed two main peaks; peak 1 possessed peroxidase activity and peak 2 contained the major band protein. These studies indicate that eosinophil granules contain a cationic protein of low molecular weight which lacks peroxidase activity and which accounts for greater than 50% of granule protein.

Marked Airway Eosinophilia Prevents Development of Airway Hyper-responsiveness During an Allergic Response in IL-5 Transgenic Mice

“…Eosinophils could dampen the acute hypersensitivity response, especially by inhibiting mast cell products (2, 3). However, by 1980, the discoveries of eosinophil cationic protein and eosinophil MBP (34) led to the hypothesis that eosinophils are proinflammatory cells involved in defense against large organisms, such as helminth parasites (4). Eosinophils can also make lipid mediators and produce oxygen metabolites (4,5), and these proinflammatory roles of eosinophils may be involved in the pathophysiology of human asthma and allergic diseases.…”

The Role of the Eosinophil Granulocyte in the Inflammatory Reaction

“…It was claimed to have a weak antihistamine effect. Further characterization was reported in the elegant work of Gleich et al (29,30), who isolated a major basic protein of eosinophil granules from guinea pigs. This accounted for greater than 50% of the total granule protein.…”

81. Localization of the guinea pig eosinophil major basic protein to the core of the granule

“…Eosinophils were obtained from guinea pigs by peritoneal lavage with saline, and granules were prepared as previously described (11,13). The lavage fluids containing -45% eosinophils or the purified eosinophil granules were fixed in 4% formalin in 0.1 M KH2PO4-Na2HPO4, pH 7.4, for 2 or 4 h at 23~…”

“…Eosinophil granules were prepared from guinea pig eosinophils essentially as described previously (12,13). Briefly, peritoneal cells were subjected to hypotonic lysis by suspension in 0.046 M sodium chloride for 1 min, after which the osmolality was reconstituted by addition of 10-fold concentrated PBS.…”

“…We have isolated a major basis protein (MBP) 1 from eosinophil granules of guinea pigs (12,13), humans (14), and rats (20), and in the guinea pig this material comprises over 50% of the protein content of the granule. The MBP of the guinea pig has a mol wt of 11,000, a high arginine content (13%), and readily aggregates through oxidation of its two free sulfhydryl groups.…”