The project aims to study gene expression in coelomocytes of Strongylocentrotus intermedius using Digital Gene Expression (DGE) technique. The coelomocytes in coelomic fluid of adult sea urchin had been considered as the main mediator of immune response. Individuals were infected by Vibrio fortis and induced by lipopolysaccharide and Peptidoglycan. Then coelomocytes were separated for DGE in order to study the immune responses of this sea uchin.