Decreased interleukin-2 receptor and cell cycle changes in murine lymphocytes exposed in vitro to low doses of cadmium chloride.
Relationships between in vitro cadmium-related cell cytotoxicity, ultrastructural changes and altered cell cycle were determined at 21-72 h after mitogenic stimulation of C57BL/6 mouse spleen lymphocytes with concanavalin A (Con A). Relatively low doses, 0.6-10 microM cadmium (Cd), added at 4 h after the mitogen activation, induced a significant cell cytotoxicity and reduced the lymphoblastic activity of the cells. Cytometric analysis of the lymphoid cell cycle at 72 h revealed that at concentrations > or = 0.6 microM Cd, the number of cells arrested in G0 + G1 phase increased, whereas the proportions of cells of the S and G2 + M phases were substantially reduced. Staining of cells with fluorescent anti-CD25 monoclonal antibody showed a cadmium-related decreased number and relative mean fluorescence of CD25+ cells, demonstrating a decreased level of interleukin-2 receptor (IL-2R). Furthermore, immunogold ultramicroscopic assay was developed for determination of intracellular interleukin-2 (IL-2) in cadmium-treated lymphocytes. The level of cytoplasmic and nuclear IL-2, localized in situ by colloidal gold ultraimmunocytochemical technique, has been estimated as markedly decreased in cells treated with > or = 1.2 microM Cd, as compared with the untreated controls. Disorganization/fragmentation of mitochondrion cristae and dilatation of cisternae of the Golgi apparatus appeared as the major ultrastructural change in 1.2 microM Cd-treated lymphocytes. Interestingly, addition of cadmium in the incubation medium, up to 4 h after mitogen activation, also interacted with lymphoproliferative mechanisms of cells in G0 + G1, S and G2 + M phase. Overall, multiple ultrastructural changes of Cd-treated lymphoid cells were clearly related with the reduced cell viability and reduced number of activated lymphoblasts.
Payette
Y
Y
Département des Sciences Biologiques and Toxen, Université du Québec, Montreal, Canada.
Lachapelle
M
M
Daniel
C
C
Bernier
J
J
Fournier
M
M
Krzystyniak
K
K
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D019256:Cadmium Chloride; D002453:Cell Cycle / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002712:Chlorides / Q000633:toxicity*; D004306:Dose-Response Relationship, Immunologic; D007376:Interleukin-2 / Q000037:antagonists & inhibitors; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015375:Receptors, Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000187:drug effects*; D013154:Spleen / Q000166:cytology / Q000187:drug effects
D002712:Chlorides; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D002104:Cadmium; D019256:Cadmium Chloride