A novel galectin cDNA (galectin-14) was cloned from ovine eosinophil-rich leukocytes by low stringency reverse transcriptase-PCR and cDNA library screening. Data base searches indicate that this gene encodes a novel prototype galectin that contains one putative carbohydrate recognition domain and exhibits most identity to galectin-9/ecalectin, a potent eosinophil chemoattractant. The sugar binding properties of the recombinant molecule were confirmed by a hemagglutination assay and lactose inhibition. The mRNA and protein of galectin-14 are expressed at high levels in eosinophilrich cell populations. Flow cytometry and cytospot staining demonstrate that the protein localizes to the cytoplasmic, but not the granular, compartment of eosinophils. In contrast, galectin-14 mRNA and protein were not detected in neutrophils, macrophages, or lymphocytes. Western blot analysis of bronchoalveolar lavage fluid indicates that galectin-14 is released from eosinophils into the lumen of the lungs after challenge with house dust mite allergen. The restricted expression of this novel galectin to eosinophils and its release into the lumen of the lung in a sheep asthma model indicates that it may play an important role in eosinophil function and allergic inflammation.The immune response of mammals to multicellular parasite infections and allergens is characterized by the recruitment of eosinophils (1, 2). The role eosinophils play in both parasite infections and allergic reactions remains controversial, and little is known of the specific function of eosinophil constituents in combating multicellular parasites or exacerbating allergic responses. The presence of eosinophils and eosinophil-derived products in the respiratory tract does, however, correlate with the pathological manifestations of allergic asthma (2-4).One of the limitations in the study of eosinophils is the scarcity of this cell population in normal individuals and the difficulty in obtaining sufficient numbers of unmanipulated cells from allergic tissues. Sheep offer a unique experimental system in which large numbers of eosinophils can be obtained using the relatively non-invasive procedure of mammary infusion of allergens followed by "milking" of the mammary gland to obtain the inflammatory cells recruited into the lumen (5, 6). Using this experimental system, the present study describes the identification of a novel galectin (galectin-14) specifically expressed by eosinophils. The expression of galectin-14 was up-regulated in the lung tissue of sensitized sheep challenged with house dust mite extract (HDM), 1 and the protein was released into the bronchoalveolar lavage (BAL) fluid.Galectins are carbohydrate binding proteins that have been increasingly implicated in both adaptive and innate immune responses. The eosinophil-specific expression of galectin-14 and its secretion into the lumen of the lung in a sheep asthma model indicates that it may play an important role in regulating the activity of eosinophils during allergic responses and further highlights the i...

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Galectins are increasingly recognised as important immunological mediators of homeostasis and disease regulation. This paper gives an overview of current knowledge of galectin involvement in parasite infection and allergic inflammation, two very different but immunologically linked phenomena. Galectins are produced by both the parasite and the host and appear to be intimately involved in parasite establishment, as well as directing the course of infection and the immune response. Host galectins have also been shown to be active participants in the recruitment of cells to sites of inflammation and modulating the effector function of mast cells, neutrophils and eosinophils. Moreover, the ability of galectins to induce differential expression of cytokine genes in leukocytes suggests that they are able to direct the nature of an adaptive immune response, in particular towards a T2-type allergic response.

Across mammalian species, human galectin-10 and ovine galectin-14 are unique in their expression in eosinophils and their release into lung and gastrointestinal tissues following allergen or parasite challenge. Recombinant galectin-14 is active in carbohydrate binding assays and has been used in this study to unravel the function of this major eosinophil constituent. In vitro cultures revealed that galectin-14 is spontaneously released by eosinophils isolated from allergen-stimulated mammary gland lavage, but not by resting peripheral blood eosinophils. Galectin-14 secretion from peripheral blood eosinophils can be induced by the same stimuli that induce eosinophil degranulation. Flow cytometric analysis showed that recombinant galectin-14 can bind in vitro to eosinophils, neutrophils and activated lymphocytes. Glycan array screening indicated that galectin-14 recognizes terminal N-acetyllactosamine residues which can be modified with alpha1-2-fucosylation and, uniquely for a galectin, prefers alpha2- over alpha2-sialylation. Galectin-14 showed the greatest affinity for lacto-N-neotetraose, an immunomodulatory oligosaccharide expressed by helminths. Galectin-14 binds specifically to laminin in vitro, and to mucus and mucus producing cells on lung and intestinal tissue sections. In vivo, galectin-14 is abundantly present in mucus scrapings collected from either lungs or gastrointestinal tract following allergen or parasite challenge, respectively. These results suggest that in vivo secretion of eosinophil galectins may be specifically induced at epithelial surfaces after recruitment of eosinophils by allergic stimuli, and that eosinophil galectins may be involved in promoting adhesion and changing mucus properties during parasite infection and allergies.

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