Superoxide production in phagocytes obtained from Mycobacterium marinum-stimulated goldfish (Carassius auratus) that were exposed to copper.
OBJECTIVE
To investigate the effects of copper exposure and recovery from copper toxicosis on the nonspecific immune response in Mycobacterium marinum-inoculated goldfish.


METHODS
Goldfish (Carassius auratus) with a mean weight of 33.5 g.


METHODS
Superoxide (O2-) production was measured in fish 2 to 6 weeks after injection with phosphate-buffered saline (PBS) solution or M marinum (10(2) to 10(7) colony-forming units [CFU]/fish). Then, paired groups of fish were injected with PBS solution or 10(4) CFU of M marinum and exposed to copper (100 microg/L) for 7 days or for 4 days with 3 days of recovery. One paired group not exposed 14 days later to copper served as control fish. Phagocyte production of O2-was measured by use of the nitroblue tetrazolium reduction assay. Inflammation and bacterial colony counts were determined by use of routine histologic and microbiologic procedures.


RESULTS
Superoxide production achieved a maximal response 2 to 4 weeks after M marinum inoculation. Compared with control fish, O2- production increased in the groups exposed to copper but then decreased in the exposed groups that were allowed to recover. Superoxide response and peritoneal inflammation were greater in M marinum-inoculated groups than in non-inoculated groups.


CONCLUSIONS
Copper exposure and inoculation with M marinum increased O2- production, whereas recovery after exposure decreased O2- production, even in fish that were immunostimulated by M marinum.


CONCLUSIONS
When the antimicrobial oxidative response is suppressed after copper exposure, steps should be taken to avoid imposing additional stress and minimize the possibility of resurgent or secondary pathogenic infections.
Jacobson
S V
SV
Aquatic Pathobiology Center, Department of Pathology, School of Medicine, University of Maryland, Baltimore 21201, USA.
Trucksis
M
M
Kane
A S
AS
Reimschuessel
R
R
D000818:Animals; D003300:Copper / Q000506:poisoning*; D005393:Fish Diseases / Q000382:microbiology / Q000503:physiopathology*; D006054:Goldfish; D007668:Kidney / Q000187:drug effects / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D009165:Mycobacterium Infections, Nontuberculous / Q000150:complications / Q000503:physiopathology / Q000662:veterinary*; D019910:Mycobacterium marinum; D010586:Phagocytes / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D011041:Poisoning / Q000150:complications / Q000503:physiopathology / Q000662:veterinary*; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D013481:Superoxides; D003300:Copper; D013755:Tetradecanoylphorbol Acetate