RESUMO
We investigated total copper (Cu2+) and zinc (Zn2+) content in plasma and peripheral blood mononuclear cells (PBMC) and its impact on proliferative ability of the latter in patients on chronic hemodialysis versus age- and sex-matched healthy volunteers. Plasma levels of Cu2+ and Zn2+ were significantly lower in dialysis patients compared with the control group (83.6 +/- 7.29 v 95.1 +/- 9.63 microg/dL, P <.03 for Cu2+; 71.1 +/- 7.64 v 89.7+/- 12.55 microg/dL, P <.005 for Zn2+). Basal total PBMC-associated Cu2+ content was significantly higher in uremic patients (19.3 +/- 3.59 v 14.6 +/- 2.72 micromol/mg protein, P <.005). Basal PBMC-associated Zn2+ concentration was also significantly elevated in hemodialysis patients compared with their healthy counterparts (23.9 +/- 5.64 v 10.5 +/- 2.64 micromol/mg protein, P <.005). In addition, we incubated PBMC of the uremic patients versus healthy control PBMC in a Zn2+ free versus Zn2+ enriched medium. After a 72-hour incubation, total cell-associated Zn2+ of both normal and uremic cell populations increased significantly compared with the respective baselines (34.6 +/- 22.49 v 4.3 +/- 1.42 and 20.3 +/- 10.71 v 5.8 +/- 2.22 micromol/mg protein, respectively). However, no statistically significant difference was evident between the 2 groups (34.6 +/- 22.49 v 20 +/- 10.7 micromol/mg protein). Total cell Zn2+ content, on the other hand, was significantly increased in uremic PBMC after 72 hours of incubation in Zn2+ enriched medium compared with the control group (63.3 +/- 26.12 v 18.6 +/- 13.42 micromol/mg protein, P <.005). A significant increase in PBMC proliferation evaluated by 3H-thymidine incorporation was evident in the Zn2+ enriched culture (35,559 +/- 4,136 counts per minute [CPM] v 20,497 +/- 7,263 CPM, P <.005). Cu2+ enrichment of the medium, while resulting in a modest elevation of cell-associated Cu2+, did not produce such a proliferative effect.