Carbohydrate-binding proteins (plant/human lectins and autoantibodies from human serum) as mediators of release of lysozyme, elastase, and myeloperoxidase from human neutrophils

Abstract

Analysis of cell surface glycosylation not only provides information about cell properties such as their state of differentiation or histogenetic lineage. The carbohydrate chains also provide potentially functional binding sites to endogenous carbohydrate-binding proteins. This interaction can elicit consequent signalling processes. Because of the importance of neutrophils in the host defence system, we monitored the effect of the binding of such sugar receptors to their cell surface on the release of the enzymatic activities of lysozyme, elastase, and myeloperoxidase. Besides the mannose-binding lectin concanavalin A and the immunomodulatory alpha/beta-galactoside-binding lectin from Viscum album L., three preparations of human sugar receptors - beta-galactoside-binding lectin (M(r) 14 kDa) and two affinity-purified polyclonal IgG fractions from serum with the capacity to recognize alpha- or beta-galactosides, respectively - were used. Two animal lectins from chicken liver and intestine that bind beta-galactosides, as well as the lectin-like human serum amyloid P component, were included in order to assess the importance of slight differences in ligand recognition. Cytochalasin B-enhanced enzyme release was invariably seen with the two plant lectins and the chicken liver beta-galactoside-binding lectin, but the related intestinal lectin did not increase enzyme release. The mammalian homologue of these avian lectins triggered lysozyme secretion, and the lactoside-binding IgG fraction enhanced the amount of extracellular elastase activity slightly but significantly. Thus, the actual lectin, not the nominal specificity of sugar receptors, is crucial for elucidation of responses. Due to the highly stimulatory activity of the two plant lectins, neutrophils from patients with non-cancerous diseases and from patients with lung cancer were monitored for the extent of lectin-mediated enzyme release. Only the concanavalin A-mediated reactivity of the neutrophils was associated with the type of disease.

The Emerging Role of Galectins and O-GlcNAc Homeostasis in Processes of Cellular Differentiation

“…This finding highlights a discrepancy between mRNA and protein levels for galectin-1, which was also noticed in an animal model of hypometabolism [ 113 ] suggesting additional regulatory mechanisms of galectin transcription and translation, e.g., miRNA-dependent galectin mRNA stability [ 114 , 115 ]. As galectin-1 is also found at high concentration in circulation, its abundance might be essential to maintain the functional activity of neutrophils by inducing plasma membrane NADPH activity and cell degranulation as we demonstrated in previous studies [ 7 , 115 , 116 , 117 ]. However, these aspects of functional activity of extracellular galectin-1 can vary in a biphasic manner depending on concentration as demonstrated for granulocytic differentiation [ 74 ] and respiratory burst of neutrophils [ 118 ].…”

Effects of recombinant human lactoferrin on calcium signaling and functional responses of human neutrophils

“…The degranulation reaction was stopped by placing the samples on ice and subsequent centrifugation for 8 min at 2,500xg. Lysozyme activity in supernatants was measured by detecting the lysis of the bacterial cells M. lysodeikticus using light transmission assay as described elsewhere [27,28]. MPO activity in the supernatants was measured spectrophotometrically using o-DA and H 2 O 2 substrates as previously described [29].…”

New Application of the Commercially Available Dye Celestine Blue B as a Sensitive and Selective Fluorescent “Turn-On” Probe for Endogenous Detection of HOCl and Reactive Halogenated Species

“…The results obtained for the receptor-dependent mechanism of neutrophil activation have shown that both H 2 O 2 production and exocytosis of MPO are prerequisites for an increase in the fluorescence intensity of the probe, which is indicative of HOCl and reactive halogenated species’ production in the cell suspension ( Figure 4 , Table 1 ).It was shown that fMLP and several plant lectins cause an increase of the CB fluorescence in neutrophil suspension only upon pre-incubation of the cells with cyt b . This occurs, most probably, due to the release of MPO from azurophilic granules and, consequently, the production of HOCl and reactive halogenated species accompanied by blocking the microfilament system of cells ( Table 1 ) [ 53 , 61 ].…”