Exposure to mercury alters early activation events in fish leukocytes.
Although fish in natural populations may carry high body burdens of both organic and inorganic mercury, the effects of this divalent metal on such lower vertebrates is poorly understood. In this report, inorganic mercury in the form of mercuric chloride (HgCl2) is shown to produce both high-dose inhibition and low-dose activation of leukocytes in a marine teleost fish, Sciaenops ocellatus. Concentrations of inorganic mercury > or = 10 microM suppressed DNA synthesis and induced rapid influx of radiolabeled calcium, as well as tyrosine phosphorylation of numerous cellular proteins. Lower concentrations (0.1-1 microM) of HgCl2 that activated cell growth also induced a slow sustained rise in intracellular calcium in cells loaded with the calcium indicator dye fura-2, but did not produce detectable tyrosine phosphorylation of leukocyte proteins. These studies support the possibility that subtoxic doses of HgCl2 may inappropriately activate teleost leukocytes, potentially altering the processes that regulate the magnitude and specificity of the fish immune response to environmental pathogens.
MacDougal
K C
KC
Department of Microbiology and Immunology, Medical University of South Carolina, Charleston 29412, USA.
Johnson
M D
MD
Burnett
K G
KG
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005399:Fishes / Q000276:immunology*; D006801:Humans; D007962:Leukocytes / Q000187:drug effects* / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D008627:Mercuric Chloride / Q000633:toxicity*; D010766:Phosphorylation; D014443:Tyrosine / Q000378:metabolism
D014443:Tyrosine; D008627:Mercuric Chloride; D002118:Calcium