Innate hemocyte responses of Malacosoma disstria larvae (C. Insecta) to antigens are modulated by intracellular cyclic AMP.
Invertebrate intracellular hemocyte signaling pathways affecting cellular-antigen responses, although defined for molluscs and some arthropods including dipteran insects, is less known for lepidopterans. Hemocytic-antigen responses of the arboreal pest lepidopteran Malacosoma disstria are linked to cAMP-dependent protein kinase A implicating cAMP in cellular hemocyte immune responses. The purpose in the present study was to determine intracellular cAMP effects on larval M. disstria hemocytes adhering to slides and bacteria. Altering adenylate cyclase and phosphodiesterase activities as well as cAMP levels in vitro and in vivo changed hemocyte responses to antigens. Quiescent hemocytes had high cAMP levels due to adenylate cyclase activity and possibly low phosphodiesterase (type 4) activity. Antigen contact diminished hemocytic cAMP levels. Inhibiting adenylate cyclase increased hemocyte-antigen and hemocyte-hemocyte adhesion, the latter producing nodules in vivo without bacterial antigens. Inhibiting phosphodiesterase type 4 produced the reverse effects. Pharmacologically increasing intracellular cAMP in attached hemocytes caused many of the cells to detach. Diminished intracellular cAMP changed hemograms in vivo in bacteria-free larvae comparable to changes induced by the bacterium, Bacillus subtilis, by producing nodules. Lowering cAMP enhanced also the removal of Xenorhabdus nematophila and B. subtilisin vivo.
Gulii
Vladislav
V
Department of Natural Resource Sciences, McGill University, Montreal, Canada.
Dunphy
Gary B
GB
Mandato
Craig A
CA
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001412:Bacillus subtilis; D001424:Bacterial Infections / Q000276:immunology; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D002452:Cell Count; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000276:immunology / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000378:metabolism; D004789:Enzyme Activation / Q000276:immunology; D004794:Enzyme Repression / Q000276:immunology; D006434:Hemocytes / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D007109:Immunity; D019476:Insect Proteins / Q000378:metabolism; D007814:Larva / Q000276:immunology / Q000382:microbiology; D007915:Lepidoptera / Q000201:enzymology / Q000276:immunology* / Q000382:microbiology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D020593:Xenorhabdus
D000942:Antigens, Bacterial; D019476:Insect Proteins; D000242:Cyclic AMP; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D000262:Adenylyl Cyclases