The effect of reconstitution with cryopreserved thymocytes on thein vivoantibody response to sheep red blood cells,Aeromonas salmonicida, and DNP-KLH, in adult long term thymectomised rainbow trout (Oncorhynchus mykiss)

The effect of long term adult thymectomy, and subsequent reconstitution with autogenic cryopreserved thymocytes, on thein vivoantibody response to the thymus dependent (TD) antigens (DNP-KLH and SRBC) and thymus independent (TI) antigen (A. salmonicida) was examined in rainbow trout,Oncorhynchus mykiss. Thymectomy eight months prior to primary immunis-ation led to a reduced secondary response to SRBC and DNP-KLH, which was partly restored when the fish were reconstituted with their own cryopreserved thymocytes one week before secondary immunisation. In contrast eight month thymectomy produced an elevated secondary antibody response toA. salmonicida. This again was partly returned to control levels by reconstitution with the fishʹs autogenic cryopreserved thymocytes one week prior to secondary immunisation. The data provide evidence for a T-helper cell population, involved in the memory response to TD antigens, and for T-suppressor cell activity to TI antigens.