Annelida: Hirudinea (Leeches): Heterogeneity in Leech Immune Responses

The chapter provides a comprehensive picture of some of the most significant information on the type of cells and mechanisms involved in the regulation of the inflammation, immune response and tissue regeneration processes in the medicinal leech. This Annelid represents a useful experimental model to investigate the immune system, being cost-effective, easily manipulable and devoid of significant ethical considerations and regulatory restrictions in relation to its use. Moreover, this invertebrate model shows an innate immune response and a wound healing process characterized by the same responses observed in vertebrates, involving the same cellular mechanisms and also the same types of molecules - as specific growth factors - playing a pivotal role for guiding, controlling and regulating the angiogenesis and the innate immune response.