COMPARATIVE PROPERTIES OF CHARCOT-LEYDEN CRYSTAL PROTEIN AND MAJOR BASIC-PROTEIN FROM HUMAN EOSINOPHILS

Guinea pig eosinophil granules contain a protein, the major basic protein (MBP), which accounts for more than half of the total granule protein, has a high content of arginine and displays a remarkable tendency to form disulfide-linked aggregates. A similar protein from human eosinophil granules was purified and compared with the protein comprising the Charcot-Leyden crystal (CLC). Eosinophils from patients with various diseases were purified and disrupted, and the granule fraction was obtained. Examination of the granule fraction by transmission electron microscopy showed numerous typical eosinophil granules. Analyses of granule lysates by gel filtration and by polyacrylamide gel electrophoresis revealed the presence of peroxidase and MBP with properties similar to that previously found in guinea pig eosinophil granules. The human MBP had a molecular weight of 9200, contained less than 1% carbohydrate, was rich in arginine and readily formed disulfide-bonded aggregates. CLC were prepared from eosinophil-rich cell suspensions by homogenization in hypotonic saline. The supernates following centrifugation of cell debris spontaneously formed CLC. Analysis of CLC revealed the presence of a protein with a molecular weight of 13,000 containing 1.2% carbohydrate. The protein displayed a remarkable tendency to aggregate even in the presence of 0.2 M acetic acid. Human MBP and CLC protein differed in their molecular weights, carbohydrate compositions and amino acid analyses. Mixtures of the MBP and CLC protein yielded 2 bands in polyacrylamide gel electrophoresis. Neither eosinophil protein increased vascular permeability in the guinea pig skin or contracted the guinea pig ileum. The human MBP and the CLC are apparently distinct substances with properties such that one cannot be derived from the other.