Oral and anal immunisation with alloantigen induces active cell-mediated cytotoxic responses in carp

Adaptive immune responses at mucosal surfaces of teleost fish

“…The data presented in Fig. 3 and those of two earlier reports in ginbuna crucian carp Carassius auratus langsdorfii [108] and common carp [109] clearly indicate that cellular antigens can be taken up by the gut to induce specific cytotoxicity in peripheral blood lymphocytes (PBL) [108,109] as well as in IEL. It has also been shown that repeated intestinal immunisation can suppress the cytotoxicity induced in carp PBL [110]; a phenomenon well known as oral tolerance.…”

“…Since mammalian M cells have a strong phagocytic capability, and epithelial transport takes place without the interference of degrading lysosomes, the uptake and transport of particles of different sizes should be studied to confirm the similarity of this trout cell type to mammalian M cells. Further, the uptake of PLGA particles by intestinal epithelium [135,136,140] and local cytotoxicity induced by anally intubated target cells [108,109] indicate the induction of phagocytosis, which may allow cellular antigens to pass the barrier. However, it is not known if this antigen transport occurs through specialized cells or regular enterocytes.…”

Induction of virus-specific cell-mediated cytotoxic responses of isogeneic ginbuna crucian carp, after oral immunization with inactivated virus

“…On the other hand, oral administration of antigens has found to suppress subsequent antibody responses in some fish species and this type of immunological hyporesponsiveness, termed oral tolerance, is inducible in fish under certain condition [11]. We have previously observed that repeated anal administrations of cellular antigen decrease specific cytotoxic responses in common carp, however, our results suggested that the decrease is not due to the induction of tolerance because the strong responses were induced again after parenteral immunization [55]. We have also investigated whether repeated oral administrations of antigen result in a decrease in cytotoxic activities in the treated fish, but the decrease was never observed [55].…”

Characterization of the cell-mediated cytotoxic responses of isogeneic ginbuna crucian carp induced by oral immunisation with hapten-modified cellular antigens

“…Our previous study in common carp (Cyprinus carpio) provided the first evidence that specific cell-mediated cytotoxic responses are induced by intestinal antigen administration and are as strong as the responses to parenteral immunisation [14]. We also showed that oral antigen administration can induce active responses in the treated fish [15]. These findings suggest that oral immunisation could be an effective strategy for inducing cell-mediated cytotoxic responses of fish.…”