Identification of human eosinophil lysophospholipase as the constituent of Charcot-Leyden crystals.

Abstract

Since the initial descriptions of Charcot-Leyden crystals more than 100 years ago, the presence of these slender, dipyramidal crystals in human tissues and biologic fluids has become a hallmark of eosinophilic leukocyte infiltration, especially in association with allergic and helminthic diseases. The formation of these crystals in vitro after disruption of human eosinophils, but not of other cell types, in hypotonic saline or detergent established the eosinophil as the unique cellular source of the crystalline protein. Charcot-Leyden crystals have now been found to express lysophospholipase activity (lysolecithin acylhydrolase, EC 3.1.1.5), and the solubilized Charcot-Leyden crystal protein presents a single stained protein band that is coincident with the lysophospholipase activity eluted from replicate gels on alkaline polyacrylamide gel electrophoresis. On sodium dodecyl sulfate/polyacrylamide gel electrophoresis, the solubilized Charcot-Leyden crystal protein migrates with a molecular weight of 17,400, which is comparable to that of eosinophil lysophospholipase purified chromatographically to homogeneity; further, on combination, the two proteins comigrate as a single staining band. Finally, the chromatographically purified eosinophil lysophospholipase in hypotonic buffer forms dipyramidal crystals morphologically identical to Charcot-Leyden crystals. The findings that chromatographically purified, homogeneous eosinophil lysophospholipase and Charcot-Leyden crystal protein express the same enzymatic activity, are of the same size and charge, and form crystals of identical morphology indicate that human eosinophil lysophospholipase is the constituent of Charcot-Leyden crystals.