ADAPTABILITY OF CARP NEUTROPHILIC GRANULOCYTES TO ENVIRONMENTAL TEMPERATURES - SPONTANEOUS CYTOTOXIC ACTIVITY AND CELL-ADHERENT ACTIVITY

This study observed the adaptability of carp neutrophilic granulocytes possessing spontaneous cytotoxic activity to different environmental temperatures. To study the adaptability of neutrophilic granulocytes, two different temperatures (25 degrees C and 10 degrees C) were select ed, both for rearing and for in vitro assays, in which the cytotoxicit y and the adherent rate against K562 target cells were measured. The c ytotoxicity and adherent rate of neutrophilic granulocytes from carp k ept at 25 degrees C for 30 days were higher when assayed at 25 degrees C than when assayed at 10 degrees C. On the other hand, in carp accli mated from 25 degrees C to 10 degrees C, the cytotoxicities and adhere nt rates, when assayed at 25 degrees C, decreased with increasing accl imation times, eventually becoming smaller than the values obtained wh en assayed at 10 degrees C. After the fish kept at 10 degrees C for a long period were re-acclimated to 25 degrees C, these activities assay ed at 25 degrees C again became higher than the activities assayed at 10 degrees C. These results indicated that carp neutrophilic granulocy tes adapt their cytotoxic activity and adherent activity to different environmental temperatures. A change in cellular composition in the he ad kidney was also observed in carp kept at different environmental te mperatures. The percentage of neutrophilic granulocytes became higher and lymphocytes became lower in carp that were kept at 10 degrees C fo r a long period compared with carp that were kept at 25 degrees C for a long period. (C) 1997 Academic Press Limited.