Charcot-Leyden crystal protein distribution in basophils and its absence in mast cells that differentiate from human umbilical cord blood precursor cells cultured in murine fibroblast culture supernatants or in recombinant human c-kit ligand

A Brief History of Charcot-Leyden Crystal Protein/Galectin-10 Research

Eosinophils are present in tissues, such as the respiratory tract, spleen, lymph nodes and blood vessels. The significant presence of eosinophils in these tissues are associated with various diseases, including asthma, allergies, acute myeloid leukemia, etc. Charcot-Leyden crystal protein/galectin-10 is overexpressed in eosinophils and has also been identified in basophils and macrophages. In human body, this protein could spontaneously form Charcot-Leyden crystal in lymphocytes or in the lysates of lymphocytes. At present, the role of Charcot-Leyden crystal protein/galectin-10 in lymphocytes is not fully understood. This review summarizes research progress on Charcot-Leyden crystal protein/galectin-10, with emphasis on its history, cellular distributions, relations to diseases, structures and ligand binding specificity.

Degranulation Patterns of Eosinophils in Advanced Gastric Carcinoma: An Electron Microscopic Study

Recruitment and activation of eosinophils have been studied intensely in asthma and other allergic diseases. Less is known about the infiltration and degranulation patterns of eosinophils in the tumor stroma. Seven cases of advanced gastric carcinomas were found to be massively infiltrated by eosinophils and studied by light and electron microscopy. Gastric carcinomas, despite having similar numbers of tissue eosinophils, exhibited markedly different degranulation patterns. In 2 cases, resting nondegranulating eosinophils were found. Piecemeal degranulation was the predominant mode of secretion from eosinophils localized within the tumor stroma in 4 cases. Eosinophil exocytosis and cytolysis were rarely observed. In 1 case, crystals morphologically similar to Charcot-Leyden crystals were observed at the extracellular level as well as in phagosomes of tissue macrophages, confirming active sequestrations of eosinophil Charcot-Leyden protein by macrophages in vivo. In the same case, eosinophils showed characteristic features of early and late apoptotic changes, such as condensed chromatin, focal dilatation of nuclear envelope, and preserved plasma membrane. Morphological association between apoptotic eosinophils and deposition of granules in the tumor stroma was found. Extracellular deposition of intact granules from apoptotic eosinophils was distinct from eosinophilic (necrotic) cytolysis, and has reported previously in experimental studies in vitro. To the knowledge of the authors, this case represents the first report of late apoptotic eosinophils that release their granules within the tumor stroma in a human gastric carcinoma.

Histamine content and secretion in basophils and mast cells

Biochemical determinations of the histamine content and secretion from basophils and mast cells have been available for some time, and much of the complex anatomy of these cellular populations and their release reactions has been documented using the electron microscope. The ultrastructural analyses led to the description of vesicular transport between secretory granules and the plasma membrane as a mechanism for secretion from basophils and mast cells--a process termed piecemeal degranulation. Proof of concepts incorporated in a general degranulation model put forth in 1975 (DVORAK, H.F. and DVORAK, A.M.) requires high magnification imaging of a granule constituent in trafficking vesicles in the process of a stimulated release reaction in which the constituent release is monitored biochemically. Development and application of a new enzyme-affinity method to detect histamine at high magnifications in well-preserved ultrastructural samples have provided the necessary means to establish proof that appropriate secretagogues can stimulate the vesicular transport of histamine in basophils and mast cells during release reactions monitored biochemically. The background information necessary to the understanding of this result is presented here, as well as the development and verification of the diamine oxidase-gold method to image histamine in human mast cell granules as the test system. Also presented are applications using this technology to examine histamine stores and secretion in vitro, in vivo, and ex vivo in human basophils and mast cells and in mouse mast cells. Specifically examined are histamine stores developing in maturing mast cells induced to develop de novo from cultured human cord blood cells, secretagogue-stimulated release and recovery of histamine stores from isolated, purified human lung mast cells ex vivo, cytokine-stimulated degranulation of human skin mast cells and their histamine stores in vivo, piecemeal degranulation of human gut mast cells and their histamine stores in inflammatory bowel disease in vivo, piecemeal degranulation of mouse skin mast cells and their histamine stores in inflammatory eye disease in an interleukin-4 transgenic mouse model in vivo, and the stimulated secretion and recovery of histamine from human basophils ex vivo.

Cell biology of the basophil

The cell biology of basophils, based on published studies spanning 1990-1997, is reviewed. These rarest cells of granulocyte lineages are now available in sufficient numbers for such studies to be done, based on new methods for isolating and purifying the cells from peripheral blood and organ sources and for their derivation in growth factor-containing cultures from their precursors de novo. These studies are dependent on electron microscopy for the accurate identification of basophils, studies which have recently established the presence of basophils in two new species--mice and monkeys. Secretory, endocytotic and storage properties of basophils constitute their mechanistic role(s) in human disease; their role(s) in health is, however, obscure. Development of immunoaffinity and enzyme-affinity ultrastructural labeling techniques to image the Charcot-Leyden crystal protein and histamine in human basophils, coupled with ultrastructural analysis of kinetic samples of cells obtained after stimulation with diverse secretogogues, has provided insight into the role of vesicles in secretory transport mechanisms in human basophils as well as the definition of key ultrastructural phenotypes of secreting basophils.

Ultrastructural localization of Charcot-Leyden crystal protein in human eosinophils and basophils

The Charcot-Leyden crystal (CLC) protein with lysophospholipase activity and carbohydrate-binding properties is a characteristic constituent of eosinophils and basophils. We investigated its subcellular distribution using immunoelectron microscopy. Eosinophil progenitors, mature eosinophils and basophils all contained CLC protein in their cytosol and in the euchromatin of the nucleus. A minor population of granules in eosinophils, increasing in number with maturation, and a more abundant granule-population in basophils, were found to contain CLC protein. Double-labeling experiments showed, in eosinophils, that CLC protein-containing granules contain also eosinophil peroxidase, a characteristic specific granule protein. This suggests a relationship between the CLC protein-containing organelle and the specific granule. In basophils both the CLC protein positive and the negative granules showed the same characteristic particulate-like structure of the granular matrix and both share the same membrane marker CD63. In nasal polyps, macrophages were observed phagocytosing necrotic eosinophils. In these macrophages CLC protein-containing vesicles were observed, probably representing late endosomes. The dual (cytosolic/nuclear and granular) localization of CLC protein suggests that this protein enters both a secretory and a nonsecretory pathway during its biosynthesis, indicating functional roles for this protein both within the cell and extracellularly.

Ultrastructural analysis of the development of human basophils and mast cells in vitro

The ultrastructural analysis of a variety of culture systems of human cord blood mononuclear cells (spanning a 10-year research effort) is reviewed. Human basophils, eosinophils and mast cells reliably developed from their agranular precursors that are present in human cord blood. Suspension cultures and cocultures with fibroblasts were used to examine the effects on differentiation and maturation of full (fibroblast), interleukin-2-depleted (human T cells), and murine inducer T cell culture supernatants, partially purified mouse fibroblast factor(s), recombinant human interleukins 3 and 5, and recombinant human and murine c-kit ligands (stem cell factor, mast cell growth factor). Together, these studies allowed us to define the differentiation and full maturation of the basophil and eosinophil lineages and provided evidence for the induction of a form of secretion (termed piecemeal degranulation) of the basophil and eosinophil lineages in interleukin-3- or -5-supplemented cultures. Mast cells were absent from interleukin-3- or -5-containing cultures. The development of fully mature mast cells occurred regularly in fibroblast-containing cocultures; partially mature mast cells developed in fibroblast culture supernatant-, partially purified mouse fibroblast factor(s)-, and either recombinant human or murine c-kit ligand-supplemented suspension cultures. Small numbers of basophils and eosinophils were present in the suspension cultures that received c-kit ligand in its recombinant or naturally occurring forms. Ultrastructural immunogold analyses confirmed that basophils and eosinophils contained the Charcot-Leyden crystal protein (in different subcellular locations) but that mast cells did not. In both cocultures and suspension cultures, the primary event recorded for mast cells was that of differentiation and maturation, with the ultrastructural correlates of synthetic activity and granule building prevailing. Spontaneous secretory events, recognizable by ultrastructural analysis, were not evident in either mature or partially mature mast cells developing in these cultures.