Interactions of intracellular calcium and immune response in earthworms

Intracellular calcium level has a definite role in innate and adaptive immune signaling but its evolutionary aspects are not entirely clear yet. Very few information are accessible about calcium contents of invertebrate immunocytes, especially of celomocytes, the effector cells of earthworm immunity. Different basal and induced Ca2+ levels characterize the various celomocyte subgroups. Intracellular calcium is mostly located in the endoplasmic reticulum and celomocytes exert intracellular Ca2+ ATPase activity to maintain their calcium homeostasis. Immune molecules such as phytohemagglutinin and the chemoattractant fMLP caused the elevation of intracellular Ca2+ level in celomocytes. All the evidence suggests that Ca2+ influx may play a crucial role in the signal transduction of the earthworm’s innate immunity.