Superoxide anion generation by pacific oyster (Crassostrea gigas) hemocytes: Identification by electron spin resonance spin trapping and chemiluminescence analysis

1. 1. The generation of a superoxide anion (O₂^•-) by hemocytes of the Pacific oyster, Crassostrea gigas, was investigated by using electron spin resonance spin trapping with the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and by the chemiluminescence method. 2. 2. Oyster hemocytes released O₂^•- on stimulation with phorbol myristate acetate as revealed by both methods. 3. 3. A great difference was found in O₂^•--generating activity among three subpopulations of hemocytes, which were separated from each other by using Percoll density gradients. 4. 4. Evidence obtained in our experiments suggests that a specific O₂^•--forming system, which becomes functional upon adequate stimulation, exists in a specialized subpopulation of C. gigas hemocytes similar to the professional phagocytes in mammals.