Hemocyte –hemocyte adhesion and nodulation reactions of the greater wax moth, Galleria mellonella are influenced by cholera toxin and its B-subunit

Publication date: 2012 Source:Results in Immunology, Volume 2 Author(s): Jason F. Lapointe, Gary B. Dunphy, Craig A. Mandato Nodulation, the lepidopteran insect immune response to large numbers of microbes in the blood (hemolymph) consists of the coordination of the blood cell (hemocyte) types the granular cells and plasmatocytes in terms of granular cell–bacteria adhesion and hemocyte–hemocyte adhesion (microaggregation). Hemocyte–microbe adhesion is influenced by the secondary messenger, cAMP, and cAMP-dependent protein kinase A. In the present study, cholera toxin, an AB5 protein known to indirectly stimulate adenylate cyclase, is used to examine the hemocyte responses to glass, bacteria and hemocyte–hemocyte microaggregates. In vitro, this toxin induces a bimodal hemocyte adhesion response that varies with the holotoxin concentration in terms of the individual and aggregated hemocyte adhesion responses: the lower CTX concentration (1.2nM) increases microaggregate adhesion and decreases individual hemocyte binding to glass, as does higher concentrations (6–120nM), however microaggregates induced by lower concentrations do not adhere to glass. Cholera toxin-induced microaggregation is inhibited by RGDS, suggestive of integrin involvement. In vivo, cholera toxin (1.2–120nM) injected into larvae induces also a bimodal hemocytic response: low levels (1.2–6nM) cause reduced hemocyte adhesion, while high levels (12–120nM) increase hemocyte release or mo...
Source: Results in Immunology - Category: Allergy & Immunology Source Type: research