Abstract
Changes in the number of antibody producing cells were studied by measuring plaqueforming cells (PFC) of the spleen and kidney in carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss), ayu (Plecoglossus altivelis), Japanese eel (Anguilla japonica), Japanese flounder (Paralichthys olivaceus), and red seabream (Pagrus major) after an intraperitoneal injection with Vibrio anguillarum 0-antigen. It was confirmed in carp and ayu that the injected antigen was distributed at the highest levels in the spleen and kidney 3 to 6 h after the injection. PFCs appeared in the spleen and kidney of all the fish species tested. The number of PFC reached maximum value after 8-17 days. The number of PFC in the spleen was always higher than that in the kidney in carp, rainbow trout, ayu and eel, whereas in red seabream the former was lower than the latter. There was no difference in PFC number between the two organs in the Japanese flounder.
In an additional experiment, ayu was immunized by immersing in the 0-antigen suspension (3g/l) for 30 min. As a result, no PFCs were detected in the spleen or kidney and no aggulutinating antibody was measured in the serum.
