Effect of chromium and cobalt ions on primary human lymphocytes in vitro

Figures & data

Figure 1.  Cell viability of lymphocytes following 24 (upper) and 48 (lower) h of exposure to varying concentrations of Cr⁶⁺ and Co²⁺ ions, as measured by neutral red (NR) assay. (A and C) Resting and (B and D) anti-CD3-activated lymphocytes. A value of 100% indicates unexposed control cells; results are means ± SE (n = 18). *Significantly different from control values (at p < 0.05) by one-way analysis of variance (ANOVA) followed by Dunnett’s multiple comparison test. ^†Significantly different from Co²⁺ values (at p < 0.05) by two-sample t-test.

Figure 2.  T-lymphocyte proliferation following anti-CD3 ± anti-CD28 activation and exposure to varying concentrations of Cr⁶⁺ and Co²⁺ ions for 48 h. A value of 100% indicates unexposed control cells; results are means ± SE (n = 12). *Significantly different from control values (at p < 0.05) by one-way analysis of variance (ANOVA) followed by Dunnett’s multiple comparison test.

Figure 3.  IL-2 release from anti-CD3 ± anti-CD28 activated lymphocytes exposed to varying concentrations of Cr⁶⁺ and Co²⁺ ions for 48 h. Results are means ± SE (n = 3). *Significantly different from control values (at p < 0.05) by one-way analysis of variance (ANOVA) followed by Dunnett’s multiple comparison test.

Figure 4.  IFNγ release from anti-CD3 ± anti-CD28 activated lymphocytes exposed to varying concentrations of Cr⁶⁺ and Co²⁺ ions for 48 h. Results are means ± SE (n = 3). *Significantly different from control values (at p < 0.05) by one-way analysis of variance (ANOVA) followed by Dunnett’s multiple comparison test.

Figure 5.  Resting and anti-CD3 activated lymphocytes stained with annexin V and 7-AAD following exposure to 100 µM Cr⁶⁺ and 100 µM Co²⁺ for 24 h. Viable cells were annexin V⁻ and 7-AAD⁻. Cells in early stages of apoptosis were annexin V⁺ but 7-AAD⁻, whereas cells in late stages of apoptosis were both annexin V⁺ and 7-AAD⁺.

Figure 6.  Total apoptosis in lymphocytes following 24 (upper) and 48 (lower) h of exposure to Cr⁶⁺ and Co²⁺. (A and C) Resting and (B and D) anti-CD3-activated lymphocytes. Results are mean (± SE; n = 6) proportion of lymphocytes expressing annexin V. A value of 100% indicates baseline apoptosis in unexposed control cells. *Significantly different from control values (at p < 0.05) by one-way analysis of variance (ANOVA) followed by Dunnett’s multiple comparison test. ^†Significantly different from Co²⁺ values (at p < 0.05) by two-sample t-test.

Figure 7.  Total apoptosis in lymphocytes (pre-treated for 24 h with/without caspase-3 inhibitor (50 µM Z.Devd.FMK)) following 24 h of exposure to Cr⁶⁺ or Co²⁺. (A and C) Resting and (B and D) anti-CD3-activated lymphocytes. Results are mean (± SE; n ≥ 3) proportion of lymphocytes expressing annexin V. A value of 100% indicates baseline apoptosis in unexposed control cells.