IMMUNOLOGICAL ASSESSMENT OF HYBRID STRIPED BASS AT 3 CULTURE TEMPERATURES

Hybrid striped bass (Morone saxatilis Walbaum x Morone chrysops Rafine sque) were maintained at three water temperatures (23 degrees C, 26 de grees C and 29 degrees C) within their preferred temperature range. Ph ysiological and immunological parameters were measured in each tempera ture group to determine if an optimal culture temperature exists for v arious immune functions. No differences were found in the mean haemato crit, leukocrit, and serum cortisol of the three temperature groups; h owever, changes in the relative numbers of leukocytes in the highest t emperature group were suggestive of thermal stress. Nonspecific immuni ty as evaluated by granulocyte respiratory burst activity and serum sp ontaneous haemolytic activity was found to be temperature sensitive wi th the highest responses occurring in the 26 degrees C group. Followin g immunization with trinitrophenyl-lipopolysaccharide antigen, the pas sive haemagglutinating antibody response was very rapid (3 days) at 29 degrees C but was delayed (6 days) in the 23 degrees C group, and low er numbers of plaque-forming cells were evident at 7 days post-immuniz ation in the 29 degrees C group reflecting possible faster kinetics. T he secondary in vitro plaque forming cell response trinitrophenyl-keyh ole limpet haemocyanin was also decreased in the highest temperature g roup indicating fewer memory cells or suppression of the 29 degrees C acclimated cells when stimulated at 23 degrees C in vitro. (C) 1995 Ac ademic Press Limited