I noted two really interesting studies published with one investigator in common; Professor Mary Grant in Glasgow Scotland firstname.lastname@example.org. She resides in the biomedical engineering department and specializes in Cell & Tissue Engineering,and Xenobiotic Metabolism and Toxicity.
In 2009 she published a study Response to chronic exposure to hexavalent chromium in human monocytes.
The question she reviewed was depletion of lymphocytes has been reported in vivo in patients with metallic prostheses, and correlated with elevated chromium and cobalt concentrations in blood. However, the implications for immune function were unclear. [Important because lymphocytes fight infection. Prolonged inflammation from infection can result in long term issues. ]
She assessed the in vitro responses of human monocytes to chronic exposure (4 weeks) to Cr (VI) ions at concentrations which have been measured in patients with metal artificial hip implants (0.05-0.5 microM). She found that chronic exposure to these low clinically relevant concentrations of Cr (VI) induced a potent adaptive response on a cellular level and concluded that such direct toxicity of Cr ions may contribute to the effects of metal implants on lymphocyte populations in vivo.
In May of 2011, she was a co author of another journal article; Effect of chromium and cobalt ions on primary human lymphocytes in vitro.
The exposure of resting lymphocytes to 100 µM Co(2+) resulted in significant decrease in cell viability accompanied by a significant increase in apoptosis (cell death.) The results indicate that exposure to high concentrations of metal ions initiate apoptosis that results in decreased lymphocyte proliferation (can’t fight infection/compromised immune system.)Her conclusion: metal ion concentrations not directly cytotoxic to lymphocytes may affect events at a molecular level, thereby impeding lymphocyte proliferation. Hence, this may contribute to altered immune system function in patients with Co-Cr implants.
You would think that studying Cr 6 is a non issue for orthopedic implants. Guess not!