Natural cytotoxicity of tilapia leucocytes

Abstract

We have demonstrated the presence of natural cytotoxic cells (NCC) against the murine cell line YAC-1 in tilapia (Tilapia mossambica X T honorum) fish. NCC-activities were observed in the anterior ludney, trunk kidney, spleen and peripheral blood. The highest cytotoxicity was found in the anterior kidney while the lowest was in the blood. Macrophages form over 70 % of conjugate forming cells (CFC) in anterior and trunk kidney as well as spleen, while lymphocytes represent the main CFC in peripheral blood. The optimum temperature for NCC activity was 28°C. Maximum S'Chromium release from labelled targets was between 3 and 6 h of incubation with anterior kidney leucocytes at 2E°C. We also have evidence for the production of cytotoxic factors(s) upon coincubation with YAC-1 cells. NCC diminishes as the fish mature and age.