Raftos David A, Fabbro Megan, Nair Sham V
Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia.
Dev Comp Immunol. 2004 Mar;28(3):181-90. doi: 10.1016/s0145-305x(03)00136-8.
This study investigates the exocytic responses of invertebrate hemocytes to pathogen-associated antigens. It demonstrates that a homologue of complement component C3, a key defensive protein of the innate immune system, is expressed by phagocytic hemocytes (non-refractile vacuolated cells) of the tunicate, Styela plicata. C3-like molecules are localized in sub-cellular vesicles and are rapidly exocytosed after stimulation with bacterial, fungal or algal cell surface molecules. Signal transduction analysis indicated that the induced secretion of C3-like molecules is mediated by a G-protein dependent signaling pathway, which modulates tubulin microtubules. All of this evidence indicates that hemocytes can contribute to host defense responses by rapidly exocytosing C3-like proteins at sites of infection.
