NONSPECIFIC CELLULAR-RESPONSES OF RAINBOW-TROUT TO VIBRIO-ANGUILLARUMAND ITS EXTRACELLULAR PRODUCTS (ECPS)

We have studied the early inflammatory response induced by Vibrio angu illarum and by its extracellular products (ECPs) in rainbow trout afte r intraperitoneal injection. The results showed a very similar inflamm atory response which included leucopenia, mainly due to lymphopenia, n eutrophilia and an increase in the number of circulating monocytes. Me lanomacrophages as well as immature leucocytes were frequently observe d circulating in the blood of injected rainbow trout. Monocytes often contain phagocytosed bacteria and other, altered cells including eryth rocytes and leucocytes. However, neutrophils only occasionally phagocy tosed bacteria. Many circulating leucocytes showed important structura l alterations. Neutrophils of trout injected with bacteria and ECPs al so showed stronger PAS-staining than those of control trout as well as Dohle bodies and swollen granules. A marked vasodilatation was observ ed in the kidney and spleen which was coincidental with a mobilization of eosinophilic granular cells and an hypertrophy of sinusoidal endot helial cells showing an increase in the number of cytoplasmic granules . An increase in the number of macrophages and melanomacrophages in th e kidney and spleen as well as oedema and leucocyte infiltration in th e liver and gills were also noted.