COBALT-CHROMIUM-MOLYBDENUM BUT NOT TITANIUM-6ALUMINIUM-4VANADIUM ALLOY DISCS INHIBIT HUMAN T-CELL ACTIVATION IN-VITRO

This study describes the effect of the presence of cobalt-chromium-mol ybdenum (CoCrMo) and titanium-6aluminium-4vanadium (Ti6AL4V) disc samp les on the CD3-mediated in vitro response of human peripheral blood T lymphocytes. Lymphocyte proliferation in the presence and absence of t hese metal alloy discs was measured by [H-3]thymidine incorporation. I nhibition of lymphocyte proliferation was observed in the presence of CoCrMo disc samples, In contrast, the presence of the Ti6AL4V metal al loy discs had no effect on T cell proliferation, Ultrastructural studi es using scanning electron microscopy revealed that the differences in the number of blast cells on uncoated CoCrMo and Ti6AL4V discs from a 4 day culture were consistent with the results observed in the prolif eration experiments, i.e. fewer blast cells were seen on the CoCrMo th an on the Ti6AL4V discs, In addition, a quantitative analysis of trace elements using total reflection X-ray fluorescence spectrometry in su pernatants from 68 h in vitro cultures containing Ti6AL4V or CoCrMo di sc samples was performed, revealing differences in the relative metal concentrations in the culture conditions tested, These differences poi nt to the presence of cobalt in the supernatants as a possible determi ning factor of the inhibition observed, Because cell viability did not appear to change, a more complex mechanism involving the interaction of metals with T lymphocytes may account for the results obtained.