Induction of specific cytotoxic T-cell activity against xenogeneic target cells in carp (Cyprinus carpio)

Objective-To investigate the induction of cytotoxic T cells in carp (Cyprin us carpio) after inoculation of fish with 2 xenogeneic line cells and to ex amine specificity of the cytotoxic activity. Animals-22 carp. Procedure-Fish were inoculated with mouse myeloma line cells P3.NS-1/1Ag4.1 (NS-1) or chicken Marek's disease tumor-derived lymphoma line cells (MDCC MSB-1). Cytotoxic activity of immune lymphocytes was evaluated by incubatin g effector cells with homologous and heterologous target cells. Populations of effector cells were identified by blocking T-lymphocytes from effector cells, using anti-carp T-cell monoclonal antibody and complement. Results-Lymphocytes in blood, spleen, and head kidney of carp inoculated wi th NS-1 cells or MDCC MSB-1 cells had dose-dependent cytotoxic effects agai nst homologous target cells but not against heterologous target cells. Lymp hocytes from noninoculated carp did not have cytotoxic effects. Depletion o f Tlymphocytes in spleen cells from NS-l-inoculated carp resulted in a decr ease of cytotoxic activity against NS-1 cells. Cytotoxic activity of spleen lymphocytes from NS-l-inoculated or noninoculated carp was no? evident whe n cytotoxic rests were performed after addition of anti-NS-l carp serum. Conclusions and Clinical Relevance-inoculation with xenogeneic target cells induces a specific cytotoxic T-cell response in carp. Thus, cell-mediated immunity plays a role in defense against infection of parasitic organisms s uch as protozoa and helminths.