Ultrastructural localization of a sialic acid-specific hemolymph lectin in the hemocytes and other tissues of the hard tick Ixodes ricinus (Acari; Chelicerata)

Abstract

Lectins have been suggested to function as pattern-recognition molecules in invertebrate immune mechanisms. A lectin from the hemolymph of the tick Ixodes ricinus with main specificity for sialic acid was characterized and antibodies directed against this lectin were prepared. In this study, these antibodies were used to localize the lectin in the tissues of I. ricinus. Immunoreactivity with poly- and monoclonal antibodies was detected in the granules of both types of granular hemocytes, at the membrane of hemocytes, and at the basal laminae surrounding the hemocoel. Furthermore, cells attached to the midgut, invaginations of Géné's organ, and granular inclusions of nephrocytes were labeled. The immunoreactivity detected in hemocytes and the hemocoel lining supports the idea that the hemolymph lectin may function as a recognition molecule in the immune system of I. ricinus. Another function could be protection of eggs that are coated with secretions by Géné's organ. The lectin activity could also be involved in transmission of Borrelia burgdorferi, the causative agent of Lyme borreliosis, and the tick-borne encephalitis virus.

Lectins in the brown ear tick,Rhipicephalus appendiculatus: detection and partial characterization

“…This may help explain why some of the rbcs were agglutinated and others were not and suggests that the lectins recognize carbohydrate structures on the surface of the cells that are present in some cells and absent from others. This also implies that the lectins function as recognition molecules as observed earler (Kuhn et al, 1996). The hemolymph and gut lectins have also been shown to be inhibited at 1), (1-4) or 1-6) linked glucose based dissacharides or glucose and its linkages to fructose.…”

Molecular cloning and comparative analysis of fibrinogen-related proteins from the soft tick Ornithodoros moubata and the hard tick Ixodes ricinus

“…Among such proteins identified in ticks it is surprising that lectins, which are frequently implicated as mediators of non-self recognition in invertebrates , have scarcely been investigated. The presence of lectins in ticks have been shown (Grubhoffer and Mat'ha 1991;Veres and Grubhoffer, 1990;Kuhn et al, 1996) but only Dorin M (Grubhoffer and Kova´rˇ, 1998;Kova´rˇet al, 2000), which has been isolated from the hemolymph of the soft tick O. moubata, has been sequenced (Rego et al, in press). Considering that genome sequencing studies in ticks have been kept down to only salivary gland studies (Leboulle et al, 2002), a bioinformatics approach, which uses the strength of homology among such lectins, to identify and sequence them in ticks is a method that would help in further enhancing studies dealing with comparative sequence analyses which need elucidation.…”

Innate Immunity in Ticks: A review

“…The midgut of Ixodes ricinus was shown to have hemagglutination activity that was induced by feeding and not detected in starved ticks (Uhlir et al, 1996). Kuhn et al (1996) showed immunoreactivity with poly-and monoclonal antibodies of a lectin from the hemolymph in both types of granular hemocytes, at the basal laminae surrounding the hemocoel, in cells attached to the midgut, in the invaginations of Géné's organ and in granular inclusions of nephrocytes. They concluded hemolymph lectins function as recognition molecules in the immune system of I. ricinus but they also proposed that lectin activity may be involved in the transmission of Borrelia burgdorferi.…”